--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/redisplay.c	Mon Aug 13 11:28:15 2007 +0200
@@ -0,0 +1,9461 @@
+/* Display generation from window structure and buffer text.
+   Copyright (C) 1994, 1995, 1996 Board of Trustees, University of Illinois.
+   Copyright (C) 1995 Free Software Foundation, Inc.
+   Copyright (C) 1995, 1996 Ben Wing.
+   Copyright (C) 1995 Sun Microsystems, Inc.
+   Copyright (C) 1996 Chuck Thompson.
+
+This file is part of XEmacs.
+
+XEmacs is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+XEmacs is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with XEmacs; see the file COPYING.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* Synched up with:  Not in FSF. */
+
+/* Author: Chuck Thompson */
+
+/* Fixed up by Ben Wing for Mule */
+
+/* This file has been Mule-ized. */
+
+/*****************************************************************************
+ The Golden Rules of Redisplay
+
+ First:		It Is Better To Be Correct Than Fast
+ Second:	Thou Shalt Not Run Elisp From Within Redisplay
+ Third:		It Is Better To Be Fast Than Not To Be
+ ****************************************************************************/
+
+#include <config.h>
+#include "lisp.h"
+#include <limits.h>
+
+#include "buffer.h"
+#include "commands.h"
+#include "debug.h"
+#include "device.h"
+#include "elhash.h"
+#include "extents.h"
+#include "faces.h"
+#include "frame.h"
+#include "glyphs.h"
+#include "gutter.h"
+#include "insdel.h"
+#include "menubar.h"
+#include "objects.h"
+#include "process.h"
+#include "redisplay.h"
+#include "toolbar.h"
+#include "window.h"
+#include "line-number.h"
+#ifdef FILE_CODING
+#include "file-coding.h"
+#endif
+
+#ifdef HAVE_TTY
+#include "console-tty.h"
+#ifdef HAVE_UNISTD_H
+#include <unistd.h> /* for isatty() */
+#endif
+#endif /* HAVE_TTY */
+
+/* Note: We have to be careful throughout this code to properly handle
+   and differentiate between Bufbytes and Emchars.
+
+   Since strings are generally composed of Bufbytes, I've taken the tack
+   that any contiguous set of Bufbytes is called a "string", while
+   any contiguous set of Emchars is called an "array". */
+
+/* Return value to indicate a failure by an add_*_rune routine to add
+   a rune, but no propagation information needs to be returned. */
+#define ADD_FAILED (prop_block_dynarr *) 1
+
+#define BEGIN_GLYPHS	0
+#define END_GLYPHS	1
+#define LEFT_GLYPHS	2
+#define RIGHT_GLYPHS	3
+
+/* Set the vertical clip to 0 if we are currently updating the line
+   start cache.  Otherwise for buffers of line height 1 it may fail to
+   be able to work properly because regenerate_window will not layout
+   a single line.  */
+#define VERTICAL_CLIP(w, display)					\
+  (updating_line_start_cache						\
+   ? 0									\
+   : ((WINDOW_TTY_P (w) | (!display && scroll_on_clipped_lines))	\
+      ? INT_MAX								\
+      : vertical_clip))
+
+/* The following structures are completely private to redisplay.c so
+   we put them here instead of in a header file, for modularity. */
+
+/* NOTE: Bytinds not Bufpos's in this structure. */
+
+typedef struct position_redisplay_data_type
+{
+  /* This information is normally filled in by the create_*_block
+     routines and is used by the add_*_rune routines. */
+  Lisp_Object window;
+  /* if we are working with strings rather than buffers we need a
+     handle to the string */
+  Lisp_Object string;
+  struct device *d;
+  struct display_block *db;
+  struct display_line *dl;
+  Emchar ch;		/* Character that is to be added.  This is
+			   used to communicate this information to
+			   add_emchar_rune(). */
+  Lisp_Object last_charset; /* The charset of the previous character.
+			       Used to optimize some lookups -- we
+			       only have to do some things when
+			       the charset changes. */
+  face_index last_findex;   /* The face index of the previous character.
+			       Needed to ensure the validity of the
+			       last_charset optimization. */
+
+  int last_char_width;	/* The width of the previous character. */
+  int font_is_bogus;	/* If true, it means we couldn't instantiate
+			   the font for this charset, so we substitute
+			   ~'s from the ASCII charset. */
+  Bytind bi_bufpos;
+  Bytind bi_endpos;
+  int pixpos;
+  int max_pixpos;
+  int blank_width;	/* Width of the blank that is to be added.
+			   This is used to communicate this information
+			   to add_blank_rune().
+
+			   This is also used rather cheesily to
+			   communicate the width of the eol-cursor-size
+			   blank that exists at the end of the line.
+			   add_emchar_rune() is called cheesily with
+			   the non-printing char '\n', which is stuck
+			   in the output routines with its width being
+			   BLANK_WIDTH. */
+  Bytind bi_cursor_bufpos;/* This stores the buffer position of the cursor. */
+  unsigned int cursor_type :3;
+  int cursor_x;		/* rune block cursor is at */
+  int start_col;	/* Number of character columns (each column has
+			   a width of the default char width) that still
+			   need to be skipped.  This is used for horizontal
+			   scrolling, where a certain number of columns
+			   (those off the left side of the screen) need
+			   to be skipped before anything is displayed. */
+  Bytind bi_start_col_enabled;
+  int start_col_xoffset;	/* Number of pixels that still need to
+			   be skipped.  This is used for
+			   horizontal scrolling of glyphs, where we want 
+			   to be able to scroll over part of the glyph. */
+
+  int hscroll_glyph_width_adjust;  /* how much the width of the hscroll
+				      glyph differs from space_width (w).
+				      0 if no hscroll glyph was used,
+				      i.e. the window is not scrolled
+				      horizontally.  Used in tab
+				      calculations. */
+
+  /* Information about the face the text should be displayed in and
+     any begin-glyphs and end-glyphs. */
+  struct extent_fragment *ef;
+  face_index findex;
+
+  /* The height of a pixmap may either be predetermined if the user
+     has set a baseline value, or it may be dependent on whatever the
+     line ascent and descent values end up being, based just on font
+     information.  In the first case we can immediately update the
+     values, thus their inclusion here.  In the last case we cannot
+     determine the actual contribution to the line height until we
+     have finished laying out all text on the line.  Thus we propagate
+     the max height of such pixmaps and do a final calculation after
+     all text has been added to the line. */
+  int new_ascent;
+  int new_descent;
+  int max_pixmap_height;
+
+  Lisp_Object result_str; /* String where we put the result of
+			     generating a formatted string in the modeline. */
+  int is_modeline; /* Non-zero if we're generating the modeline. */
+  Charcount modeline_charpos; /* Number of chars used in result_str so far;
+				 corresponds to bytepos. */
+  Bytecount bytepos; /* Number of bytes used in result_str so far.
+		        We don't actually copy the bytes into result_str
+			until the end because we don't know how big the
+			string is going to be until then. */
+} pos_data;
+
+enum prop_type
+{
+  PROP_STRING,
+  PROP_CHAR,
+  PROP_MINIBUF_PROMPT,
+  PROP_BLANK
+};
+
+/* Data that should be propagated to the next line.  Either a single
+   Emchar or a string of Bufbyte's.
+
+   The actual data that is propagated ends up as a Dynarr of these
+   blocks.
+
+   #### It's unclean that both Emchars and Bufbytes are here.
+   */
+
+typedef struct prop_block prop_block;
+struct prop_block
+{
+  enum prop_type type;
+
+  union data
+  {
+    struct
+    {
+      Bufbyte *str;
+      Bytecount len; /* length of the string. */
+    } p_string;
+
+    struct
+    {
+      Emchar ch;
+      Bytind bi_cursor_bufpos; /* NOTE: is in Bytinds */
+      unsigned int cursor_type :3;
+    } p_char;
+
+    struct
+    {
+      int width;
+      face_index findex;
+    } p_blank;
+  } data;
+};
+
+typedef struct
+{
+  Dynarr_declare (prop_block);
+} prop_block_dynarr;
+
+
+static void generate_formatted_string_db (Lisp_Object format_str,
+					  Lisp_Object result_str,
+					  struct window *w,
+					  struct display_line *dl,
+					  struct display_block *db,
+					  face_index findex, int min_pixpos,
+					  int max_pixpos, int type);
+static Charcount generate_fstring_runes (struct window *w, pos_data *data,
+					 Charcount pos, Charcount min_pos,
+					 Charcount max_pos, Lisp_Object elt,
+					 int depth, int max_pixsize,
+					 face_index findex, int type);
+static prop_block_dynarr *add_glyph_rune (pos_data *data,
+					  struct glyph_block *gb,
+					  int pos_type, int allow_cursor,
+					  struct glyph_cachel *cachel);
+static Bytind create_text_block (struct window *w, struct display_line *dl,
+				 Bytind bi_start_pos, prop_block_dynarr **prop,
+				 int type);
+static int create_overlay_glyph_block (struct window *w,
+				       struct display_line *dl);
+static void create_left_glyph_block (struct window *w,
+				     struct display_line *dl,
+				     int overlay_width);
+static void create_right_glyph_block (struct window *w,
+				      struct display_line *dl);
+static void redisplay_windows (Lisp_Object window, int skip_selected);
+static void decode_mode_spec (struct window *w, Emchar spec, int type);
+static void free_display_line (struct display_line *dl);
+static void update_line_start_cache (struct window *w, Bufpos from, Bufpos to,
+				     Bufpos point, int no_regen);
+static int point_visible (struct window *w, Bufpos point, int type);
+
+/* This used to be 10 but 30 seems to give much better performance. */
+#define INIT_MAX_PREEMPTS	30
+static int max_preempts;
+
+#define REDISPLAY_PREEMPTION_CHECK					\
+((void)									\
+ (preempted =								\
+  (!disable_preemption &&						\
+   ((preemption_count < max_preempts) || !NILP (Vexecuting_macro)) &&	\
+   (!INTERACTIVE || detect_input_pending ()))))
+
+/*
+ * Redisplay global variables.
+ */
+
+/* We need a third set of display structures for the cursor motion
+   routines.  We used to just give each window a third set.  However,
+   we always fully regenerate the structures when needed so there
+   isn't any reason we need more than a single set. */
+display_line_dynarr *cmotion_display_lines;
+
+/* Used by generate_formatted_string.  Global because they get used so
+   much that the dynamic allocation time adds up. */
+static Emchar_dynarr *formatted_string_emchar_dynarr;
+static struct display_line formatted_string_display_line;
+/* We store the extents that we need to generate in a Dynarr and then
+   frob them all on at the end of generating the string.  We do it
+   this way rather than adding them as we generate the string because
+   we don't store the text into the resulting string until we're done
+   (to avoid having to resize the string multiple times), and we don't
+   want to go around adding extents to a string when the extents might
+   stretch off the end of the string. */
+static EXTENT_dynarr *formatted_string_extent_dynarr;
+static Bytecount_dynarr *formatted_string_extent_start_dynarr;
+static Bytecount_dynarr *formatted_string_extent_end_dynarr;
+
+
+/* #### probably temporary */
+int cache_adjustment;
+
+/* This holds a string representing the text corresponding to a single
+   modeline % spec. */
+static Bufbyte_dynarr *mode_spec_bufbyte_string;
+
+int in_display;		/* 1 if in redisplay.  */
+
+int disable_preemption;	/* Used for debugging redisplay and for
+			   force-redisplay. */
+
+/* We only allow max_preempts preemptions before we force a redisplay. */
+static int preemption_count;
+
+/* Minimum pixel height of clipped bottom display line. */
+int vertical_clip;
+
+/* Minimum visible pixel width of clipped glyphs at right margin. */
+int horizontal_clip;
+
+/* Set if currently inside update_line_start_cache. */
+static int updating_line_start_cache;
+
+/* Nonzero means reading single-character input with prompt
+   so put cursor on minibuffer after the prompt.  */
+int cursor_in_echo_area;
+Lisp_Object Qcursor_in_echo_area;
+
+/* Nonzero means truncate lines in all windows less wide than the frame */
+int truncate_partial_width_windows;
+
+/* non-nil if a buffer has changed since the last time redisplay completed */
+int buffers_changed;
+int buffers_changed_set;
+
+/* non-nil if hscroll has changed somewhere or a buffer has been
+   narrowed or widened */
+int clip_changed;
+int clip_changed_set;
+
+/* non-nil if any extent has changed since the last time redisplay completed */
+int extents_changed;
+int extents_changed_set;
+
+/* non-nil if any face has changed since the last time redisplay completed */
+int faces_changed;
+
+/* Nonzero means some frames have been marked as garbaged */
+int frame_changed;
+
+/* non-zero if any of the builtin display glyphs (continuation,
+   hscroll, control-arrow, etc) is in need of updating
+   somewhere. */
+int glyphs_changed;
+int glyphs_changed_set;
+
+/* non-zero if any displayed subwindow is in need of updating
+   somewhere. */
+int subwindows_changed;
+int subwindows_changed_set;
+
+/* non-zero if any displayed subwindow is in need of updating
+   somewhere. */
+int subwindows_state_changed;
+int subwindows_state_changed_set;
+
+/* This variable is 1 if the icon has to be updated.
+ It is set to 1 when `frame-icon-glyph' changes. */
+int icon_changed;
+int icon_changed_set;
+
+/* This variable is 1 if the menubar widget has to be updated.
+ It is set to 1 by set-menubar-dirty-flag and cleared when the widget
+ has been updated. */
+int menubar_changed;
+int menubar_changed_set;
+
+/* true iff we should redraw the modelines on the next redisplay */
+int modeline_changed;
+int modeline_changed_set;
+
+/* non-nil if point has changed in some buffer since the last time
+   redisplay completed */
+int point_changed;
+int point_changed_set;
+
+/* non-nil if some frame has changed its size */
+int size_changed;
+
+/* non-nil if some device has signaled that it wants to change size */
+int asynch_device_change_pending;
+
+/* non-nil if any toolbar has changed */
+int toolbar_changed;
+int toolbar_changed_set;
+
+/* non-nil if any gutter has changed */
+int gutter_changed;
+int gutter_changed_set;
+
+/* non-nil if any window has changed since the last time redisplay completed */
+int windows_changed;
+
+/* non-nil if any frame's window structure has changed since the last
+   time redisplay completed */
+int windows_structure_changed;
+
+/* If non-nil, use vertical bar cursor. */
+Lisp_Object Vbar_cursor;
+Lisp_Object Qbar_cursor;
+
+
+int visible_bell;	/* If true and the terminal will support it
+			   then the frame will flash instead of
+			   beeping when an error occurs */
+
+/* Nonzero means no need to redraw the entire frame on resuming
+   a suspended Emacs.  This is useful on terminals with multiple pages,
+   where one page is used for Emacs and another for all else. */
+int no_redraw_on_reenter;
+
+Lisp_Object Vwindow_system;	/* nil or a symbol naming the window system
+				   under which emacs is running
+				   ('x is the only current possibility) */
+Lisp_Object Vinitial_window_system;
+
+Lisp_Object Vglobal_mode_string;
+
+/* The number of lines scroll a window by when point leaves the window; if
+  it is <=0 then point is centered in the window */
+int scroll_step;
+
+/* Scroll up to this many lines, to bring point back on screen. */
+int scroll_conservatively;
+
+/* Marker for where to display an arrow on top of the buffer text.  */
+Lisp_Object Voverlay_arrow_position;
+/* String to display for the arrow.  */
+Lisp_Object Voverlay_arrow_string;
+
+Lisp_Object Vwindow_size_change_functions;
+Lisp_Object Vwindow_scroll_functions;
+Lisp_Object Qredisplay_end_trigger_functions, Vredisplay_end_trigger_functions;
+
+#define INHIBIT_REDISPLAY_HOOKS  /* #### Until we've thought about
+				    this more. */
+#ifndef INHIBIT_REDISPLAY_HOOKS
+/* #### Chuck says: I think this needs more thought.
+   Think about this for 19.14. */
+Lisp_Object Vpre_redisplay_hook, Vpost_redisplay_hook;
+Lisp_Object Qpre_redisplay_hook, Qpost_redisplay_hook;
+#endif /* INHIBIT_REDISPLAY_HOOKS */
+
+static int last_display_warning_tick, display_warning_tick;
+Lisp_Object Qdisplay_warning_buffer;
+int inhibit_warning_display;
+
+Lisp_Object Vleft_margin_width, Vright_margin_width;
+Lisp_Object Vminimum_line_ascent, Vminimum_line_descent;
+Lisp_Object Vuse_left_overflow, Vuse_right_overflow;
+Lisp_Object Vtext_cursor_visible_p;
+
+int column_number_start_at_one;
+
+#define WINDOW_SCROLLED(w) \
+(w->hscroll > 0 || w->left_xoffset)
+
+
+/***************************************************************************/
+/*									   */
+/*              low-level interfaces onto device routines                  */
+/*									   */
+/***************************************************************************/
+
+static int
+redisplay_text_width_emchar_string (struct window *w, int findex,
+				    Emchar *str, Charcount len)
+{
+  unsigned char charsets[NUM_LEADING_BYTES];
+  Lisp_Object window;
+
+  find_charsets_in_emchar_string (charsets, str, len);
+  XSETWINDOW (window, w);
+  ensure_face_cachel_complete (WINDOW_FACE_CACHEL (w, findex), window,
+			       charsets);
+  return DEVMETH (XDEVICE (FRAME_DEVICE (XFRAME (WINDOW_FRAME (w)))),
+		  text_width, (XFRAME (WINDOW_FRAME (w)),
+			       WINDOW_FACE_CACHEL (w, findex), str, len));
+}
+
+static Emchar_dynarr *rtw_emchar_dynarr;
+
+int
+redisplay_text_width_string (struct window *w, int findex,
+			     Bufbyte *nonreloc, Lisp_Object reloc,
+			     Bytecount offset, Bytecount len)
+{
+  if (!rtw_emchar_dynarr)
+    rtw_emchar_dynarr = Dynarr_new (Emchar);
+  Dynarr_reset (rtw_emchar_dynarr);
+
+  fixup_internal_substring (nonreloc, reloc, offset, &len);
+  if (STRINGP (reloc))
+    nonreloc = XSTRING_DATA (reloc);
+  convert_bufbyte_string_into_emchar_dynarr (nonreloc, len, rtw_emchar_dynarr);
+  return redisplay_text_width_emchar_string
+    (w, findex, Dynarr_atp (rtw_emchar_dynarr, 0),
+     Dynarr_length (rtw_emchar_dynarr));
+}
+
+int
+redisplay_frame_text_width_string (struct frame *f, Lisp_Object face,
+				   Bufbyte *nonreloc, Lisp_Object reloc,
+				   Bytecount offset, Bytecount len)
+{
+  unsigned char charsets[NUM_LEADING_BYTES];
+  Lisp_Object frame;
+  struct face_cachel cachel;
+
+  if (!rtw_emchar_dynarr)
+    rtw_emchar_dynarr = Dynarr_new (Emchar);
+  Dynarr_reset (rtw_emchar_dynarr);
+
+  fixup_internal_substring (nonreloc, reloc, offset, &len);
+  if (STRINGP (reloc))
+    nonreloc = XSTRING_DATA (reloc);
+  convert_bufbyte_string_into_emchar_dynarr (nonreloc, len, rtw_emchar_dynarr);
+  find_charsets_in_bufbyte_string (charsets, nonreloc, len);
+  reset_face_cachel (&cachel);
+  cachel.face = face;
+  XSETFRAME (frame, f);
+  ensure_face_cachel_complete (&cachel, frame, charsets);
+  return DEVMETH (XDEVICE (FRAME_DEVICE (f)),
+		  text_width, (f, &cachel, Dynarr_atp (rtw_emchar_dynarr, 0),
+			       Dynarr_length (rtw_emchar_dynarr)));
+}
+
+/* Return the display block from DL of the given TYPE.  A display line
+   can have only one display block of each possible type.  If DL does
+   not have a block of type TYPE, one will be created and added to DL. */
+
+struct display_block *
+get_display_block_from_line (struct display_line *dl, enum display_type type)
+{
+  int elt;
+  struct display_block db;
+
+  /* Check if this display line already has a block of the desired type and
+     if so, return it. */
+  if (dl->display_blocks)
+    {
+      for (elt = 0; elt < Dynarr_length (dl->display_blocks); elt++)
+	{
+	  if (Dynarr_at (dl->display_blocks, elt).type == type)
+	    return Dynarr_atp (dl->display_blocks, elt);
+	}
+
+      /* There isn't an active block of the desired type, but there
+         might still be allocated blocks we need to reuse. */
+      if (elt < Dynarr_largest (dl->display_blocks))
+	{
+	  struct display_block *dbp = Dynarr_atp (dl->display_blocks, elt);
+
+	  /* 'add' the block to the list */
+	  Dynarr_increment (dl->display_blocks);
+
+	  /* initialize and return */
+	  dbp->type = type;
+	  return dbp;
+	}
+    }
+  else
+    {
+      /* This line doesn't have any display blocks, so initialize the display
+         bock array. */
+      dl->display_blocks = Dynarr_new (display_block);
+    }
+
+  /* The line doesn't have a block of the desired type so go ahead and create
+     one and add it to the line. */
+  xzero (db);
+  db.type = type;
+  db.runes = Dynarr_new (rune);
+  Dynarr_add (dl->display_blocks, db);
+
+  /* Return the newly added display block. */
+  elt = Dynarr_length (dl->display_blocks) - 1;
+
+  return Dynarr_atp (dl->display_blocks, elt);
+}
+
+static int
+tab_char_width (struct window *w)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  int char_tab_width = XINT (b->tab_width);
+
+  if (char_tab_width <= 0 || char_tab_width > 1000) char_tab_width = 8;
+
+  return char_tab_width;
+}
+
+static int
+space_width (struct window *w)
+{
+  /* While tabs are traditional composed of spaces, for variable-width
+     fonts the space character tends to give too narrow a value.  So
+     we use 'n' instead.  Except that we don't.  We use the default
+     character width for the default face.  If this is actually
+     defined by the font then it is probably the best thing to
+     actually use.  If it isn't, we have assumed it is 'n' and have
+     already calculated its width.  Thus we can avoid a call to
+     XTextWidth on X frames by just querying the default width. */
+  return XFONT_INSTANCE
+    (WINDOW_FACE_CACHEL_FONT (w, DEFAULT_INDEX, Vcharset_ascii))->width;
+}
+
+static int
+tab_pix_width (struct window *w)
+{
+  return space_width (w) * tab_char_width (w);
+}
+
+/* Given a pixel position in a window, return the pixel location of
+   the next tabstop.  Tabs are calculated from the left window edge in
+   terms of spaces displayed in the default face.  Formerly the space
+   width was determined using the currently active face.  That method
+   leads to tabstops which do not line up. */
+
+static int
+next_tab_position (struct window *w, int start_pixpos, int left_pixpos)
+{
+  int n_pos = left_pixpos;
+  int pix_tab_width = tab_pix_width (w);
+
+  /* Adjust n_pos for any hscrolling which has happened. */
+  if (WINDOW_SCROLLED (w))
+    n_pos -= space_width (w) * (w->hscroll - 1) + w->left_xoffset;
+
+  while (n_pos <= start_pixpos)
+    n_pos += pix_tab_width;
+
+  return n_pos;
+}
+
+/* For the given window, calculate the outside and margin boundaries for a
+   display line.  The whitespace boundaries must be calculated by the text
+   layout routines. */
+
+layout_bounds
+calculate_display_line_boundaries (struct window *w, int modeline)
+{
+  layout_bounds bounds;
+
+  /* Set the outermost boundaries which are the boundaries of the
+     window itself minus the gutters (and minus the scrollbars if this
+     is for the modeline). */
+  if (!modeline)
+    {
+      bounds.left_out = WINDOW_TEXT_LEFT (w);
+      bounds.right_out = WINDOW_TEXT_RIGHT (w);
+    }
+  else
+    {
+      bounds.left_out = WINDOW_MODELINE_LEFT (w);
+      bounds.right_out = WINDOW_MODELINE_RIGHT (w);
+    }
+
+  /* The inner boundaries mark where the glyph margins are located. */
+  bounds.left_in = bounds.left_out + window_left_margin_width (w);
+  bounds.right_in = bounds.right_out - window_right_margin_width (w);
+
+  /* We cannot fully calculate the whitespace boundaries as they
+     depend on the contents of the line being displayed. */
+  bounds.left_white = bounds.left_in;
+  bounds.right_white = bounds.right_in;
+
+  return bounds;
+}
+
+/* Given a display line and a starting position, ensure that the
+   contents of the display line accurately represent the visual
+   representation of the buffer contents starting from the given
+   position when displayed in the given window.  The display line ends
+   when the contents of the line reach the right boundary of the given
+   window. */
+
+static Bufpos
+generate_display_line (struct window *w, struct display_line *dl, int bounds,
+		       Bufpos start_pos, prop_block_dynarr **prop,
+		       int type)
+{
+  Bufpos ret_bufpos;
+  int overlay_width;
+  struct buffer *b = XBUFFER (WINDOW_BUFFER (w));
+
+  /* If our caller hasn't already set the boundaries, then do so now. */
+  if (!bounds)
+    dl->bounds = calculate_display_line_boundaries (w, 0);
+
+  /* Reset what this line is using. */
+  if (dl->display_blocks)
+    Dynarr_reset (dl->display_blocks);
+  if (dl->left_glyphs)
+    {
+      Dynarr_free (dl->left_glyphs);
+      dl->left_glyphs = 0;
+    }
+  if (dl->right_glyphs)
+    {
+      Dynarr_free (dl->right_glyphs);
+      dl->right_glyphs = 0;
+    }
+
+  /* We aren't generating a modeline at the moment. */
+  dl->modeline = 0;
+
+  /* Create a display block for the text region of the line. */
+  {
+    /* #### urk urk urk!!! Chuck fix this shit! */
+    Bytind hacked_up_bytind =
+      create_text_block (w, dl, bufpos_to_bytind (b, start_pos),
+			 prop, type);
+    if (hacked_up_bytind > BI_BUF_ZV (b))
+      ret_bufpos = BUF_ZV (b) + 1;
+    else
+      ret_bufpos = bytind_to_bufpos (b, hacked_up_bytind);
+  }
+  dl->bufpos = start_pos;
+  if (dl->end_bufpos < dl->bufpos)
+    dl->end_bufpos = dl->bufpos;
+
+  if (MARKERP (Voverlay_arrow_position)
+      && EQ (w->buffer, Fmarker_buffer (Voverlay_arrow_position))
+      && start_pos == marker_position (Voverlay_arrow_position)
+      && (STRINGP (Voverlay_arrow_string)
+	  || GLYPHP (Voverlay_arrow_string)))
+    {
+      overlay_width = create_overlay_glyph_block (w, dl);
+    }
+  else
+    overlay_width = 0;
+
+  /* If there are left glyphs associated with any character in the
+     text block, then create a display block to handle them. */
+  if (dl->left_glyphs != NULL && Dynarr_length (dl->left_glyphs))
+    create_left_glyph_block (w, dl, overlay_width);
+
+  /* If there are right glyphs associated with any character in the
+     text block, then create a display block to handle them. */
+  if (dl->right_glyphs != NULL && Dynarr_length (dl->right_glyphs))
+    create_right_glyph_block (w, dl);
+
+  /* In the future additional types of display blocks may be generated
+     here. */
+
+  w->last_redisplay_pos = ret_bufpos;
+
+  return ret_bufpos;
+}
+
+/* Adds an hscroll glyph to a display block.  If this is called, then
+   the block had better be empty.
+
+   Yes, there are multiple places where this function is called but
+   that is the way it has to be.  Each calling function has to deal
+   with bi_start_col_enabled a little differently depending on the
+   object being worked with. */
+
+static prop_block_dynarr *
+add_hscroll_rune (pos_data *data)
+{
+  struct glyph_block gb;
+  prop_block_dynarr *retval;
+  Bytind bi_old_cursor_bufpos = data->bi_cursor_bufpos;
+  unsigned int old_cursor_type = data->cursor_type;
+  Bytind bi_old_bufpos = data->bi_bufpos;
+
+  if (data->cursor_type == CURSOR_ON
+      && data->bi_cursor_bufpos >= data->bi_start_col_enabled
+      && data->bi_cursor_bufpos <= data->bi_bufpos)
+    {
+      data->bi_cursor_bufpos = data->bi_start_col_enabled;
+    }
+  else
+    {
+      data->cursor_type = NO_CURSOR;
+    }
+
+  data->bi_endpos = data->bi_bufpos;
+  data->bi_bufpos = data->bi_start_col_enabled;
+
+  gb.extent = Qnil;
+  gb.glyph = Vhscroll_glyph;
+  {
+    int oldpixpos = data->pixpos;
+    retval = add_glyph_rune (data, &gb, BEGIN_GLYPHS, 1,
+			     GLYPH_CACHEL (XWINDOW (data->window),
+					   HSCROLL_GLYPH_INDEX));
+    data->hscroll_glyph_width_adjust =
+      data->pixpos - oldpixpos - space_width (XWINDOW (data->window));
+  }
+  data->bi_endpos = 0;
+  data->bi_cursor_bufpos = bi_old_cursor_bufpos;
+  data->cursor_type = old_cursor_type;
+  data->bi_bufpos = bi_old_bufpos;
+
+  data->bi_start_col_enabled = 0;
+  return retval;
+}
+
+/* Adds a character rune to a display block.  If there is not enough
+   room to fit the rune on the display block (as determined by the
+   MAX_PIXPOS) then it adds nothing and returns ADD_FAILED. */
+
+static prop_block_dynarr *
+add_emchar_rune (pos_data *data)
+{
+  struct rune rb, *crb;
+  int width, local;
+
+  if (data->start_col)
+    {
+      data->start_col--;
+
+      if (data->start_col)
+	return NULL;
+    }
+
+  if (data->bi_start_col_enabled)
+    {
+      return add_hscroll_rune (data);
+    }
+
+  if (data->ch == '\n')
+    {
+      data->font_is_bogus = 0;
+      /* Cheesy end-of-line pseudo-character. */
+      width = data->blank_width;
+    }
+  else
+    {
+      Lisp_Object charset = CHAR_CHARSET (data->ch);
+      if (!EQ (charset, data->last_charset) ||
+	  data->findex != data->last_findex)
+	{
+	  /* OK, we need to do things the hard way. */
+	  struct window *w = XWINDOW (data->window);
+	  struct face_cachel *cachel = WINDOW_FACE_CACHEL (w, data->findex);
+	  Lisp_Object font_instance =
+	    ensure_face_cachel_contains_charset (cachel, data->window,
+						 charset);
+	  struct Lisp_Font_Instance *fi;
+
+	  if (EQ (font_instance, Vthe_null_font_instance))
+	    {
+	      font_instance = FACE_CACHEL_FONT (cachel, Vcharset_ascii);
+	      data->font_is_bogus = 1;
+	    }
+	  else
+	    data->font_is_bogus = 0;
+
+	  fi = XFONT_INSTANCE (font_instance);
+	  if (!fi->proportional_p)
+	    /* sweetness and light. */
+	    data->last_char_width = fi->width;
+	  else
+	    data->last_char_width = -1;
+	  data->new_ascent  = max (data->new_ascent,  (int) fi->ascent);
+	  data->new_descent = max (data->new_descent, (int) fi->descent);
+	  data->last_charset = charset;
+	  data->last_findex = data->findex;
+	}
+
+      width = data->last_char_width;
+      if (width < 0)
+	{
+	  /* bummer.  Proportional fonts. */
+	  width = redisplay_text_width_emchar_string (XWINDOW (data->window),
+						      data->findex,
+						      &data->ch, 1);
+	}
+    }
+
+  if (data->max_pixpos != -1 && (data->pixpos + width > data->max_pixpos))
+    {
+      return ADD_FAILED;
+    }
+
+  if (Dynarr_length (data->db->runes) < Dynarr_largest (data->db->runes))
+    {
+      crb = Dynarr_atp (data->db->runes, Dynarr_length (data->db->runes));
+      local = 0;
+    }
+  else
+    {
+      crb = &rb;
+      local = 1;
+    }
+
+  crb->findex = data->findex;
+  crb->xpos = data->pixpos;
+  crb->width = width;
+  if (data->bi_bufpos)
+    {
+      if (NILP (data->string))
+	crb->bufpos =
+	  bytind_to_bufpos (XBUFFER (WINDOW_BUFFER (XWINDOW (data->window))),
+			    data->bi_bufpos);
+      else
+	crb->bufpos =
+	  bytecount_to_charcount (XSTRING_DATA (data->string), data->bi_bufpos);
+    }
+  else if (data->is_modeline)
+    crb->bufpos = data->modeline_charpos;
+  else
+    /* fuckme if this shouldn't be an abort. */
+    /* abort (); fuckme harder, this abort gets tripped quite often,
+		 in propagation and whatnot.  #### fixme */
+    crb->bufpos = 0;
+  crb->type = RUNE_CHAR;
+  crb->object.chr.ch = data->font_is_bogus ? '~' : data->ch;
+  crb->endpos = 0;
+
+  if (data->cursor_type == CURSOR_ON)
+    {
+      if (data->bi_bufpos == data->bi_cursor_bufpos)
+	{
+	  crb->cursor_type = CURSOR_ON;
+	  data->cursor_x = Dynarr_length (data->db->runes);
+	}
+      else
+	crb->cursor_type = CURSOR_OFF;
+    }
+  else if (data->cursor_type == NEXT_CURSOR)
+    {
+      crb->cursor_type = CURSOR_ON;
+      data->cursor_x = Dynarr_length (data->db->runes);
+      data->cursor_type = NO_CURSOR;
+    }
+  else if (data->cursor_type == IGNORE_CURSOR)
+    crb->cursor_type = IGNORE_CURSOR;
+  else
+    crb->cursor_type = CURSOR_OFF;
+
+  if (local)
+    Dynarr_add (data->db->runes, *crb);
+  else
+    Dynarr_increment (data->db->runes);
+
+  data->pixpos += width;
+
+  return NULL;
+}
+
+/* Given a string C_STRING of length C_LENGTH, call add_emchar_rune
+   for each character in the string.  Propagate any left-over data
+   unless NO_PROP is non-zero. */
+
+static prop_block_dynarr *
+add_bufbyte_string_runes (pos_data *data, Bufbyte *c_string,
+			  Bytecount c_length, int no_prop)
+{
+  Bufbyte *pos, *end = c_string + c_length;
+  prop_block_dynarr *prop;
+
+  /* #### This function is too simplistic.  It needs to do the same
+     sort of character interpretation (display-table lookup,
+     ctl-arrow checking), etc. that create_text_block() does.
+     The functionality to do this in that routine needs to be
+     modularized. */
+
+  for (pos = c_string; pos < end;)
+    {
+      data->ch = charptr_emchar (pos);
+
+      prop = add_emchar_rune (data);
+
+      if (prop)
+	{
+	  if (no_prop)
+	    return ADD_FAILED;
+	  else
+	    {
+	      struct prop_block pb;
+	      Bytecount len = end - pos;
+	      prop = Dynarr_new (prop_block);
+
+	      pb.type = PROP_STRING;
+	      pb.data.p_string.str = xnew_array (Bufbyte, len);
+	      strncpy ((char *) pb.data.p_string.str, (char *) pos, len);
+	      pb.data.p_string.len = len;
+
+	      Dynarr_add (prop, pb);
+	      return prop;
+	    }
+	}
+      INC_CHARPTR (pos);
+      assert (pos <= end);
+    }
+
+  return NULL;
+}
+
+/* Add a single rune of the specified width.  The area covered by this
+   rune will be displayed in the foreground color of the associated
+   face. */
+
+static prop_block_dynarr *
+add_blank_rune (pos_data *data, struct window *w, int char_tab_width)
+{
+  struct rune rb;
+
+  /* If data->start_col is not 0 then this call to add_blank_rune must have
+     been to add it as a tab. */
+  if (data->start_col)
+    {
+      /* assert (w != NULL) */
+      prop_block_dynarr *retval;
+
+      /* If we have still not fully scrolled horizontally, subtract
+         the width of this tab and return. */
+      if (char_tab_width < data->start_col)
+	{
+	  data->start_col -= char_tab_width;
+	  return NULL;
+	}
+      else if (char_tab_width == data->start_col)
+	data->blank_width = 0;
+      else
+	{
+	  int spcwid = space_width (w);
+
+	  if (spcwid >= data->blank_width)
+	    data->blank_width = 0;
+	  else
+	    data->blank_width -= spcwid;
+	}
+
+      data->start_col = 0;
+      retval = add_hscroll_rune (data);
+
+      /* Could be caused by the handling of the hscroll rune. */
+      if (retval != NULL || !data->blank_width)
+	return retval;
+    }
+
+  /* Blank runes are always calculated to fit. */
+  assert (data->pixpos + data->blank_width <= data->max_pixpos);
+
+  rb.findex = data->findex;
+  rb.xpos = data->pixpos;
+  rb.width = data->blank_width;
+  if (data->bi_bufpos)
+    rb.bufpos =
+      bytind_to_bufpos (XBUFFER (WINDOW_BUFFER (XWINDOW (data->window))),
+			data->bi_bufpos);
+  else
+    /* #### and this is really correct too? */
+    rb.bufpos = 0;
+  rb.endpos = 0;
+  rb.type = RUNE_BLANK;
+
+  if (data->cursor_type == CURSOR_ON)
+    {
+      if (data->bi_bufpos == data->bi_cursor_bufpos)
+	{
+	  rb.cursor_type = CURSOR_ON;
+	  data->cursor_x = Dynarr_length (data->db->runes);
+	}
+      else
+	rb.cursor_type = CURSOR_OFF;
+    }
+  else if (data->cursor_type == NEXT_CURSOR)
+    {
+      rb.cursor_type = CURSOR_ON;
+      data->cursor_x = Dynarr_length (data->db->runes);
+      data->cursor_type = NO_CURSOR;
+    }
+  else
+    rb.cursor_type = CURSOR_OFF;
+
+  Dynarr_add (data->db->runes, rb);
+  data->pixpos += data->blank_width;
+
+  return NULL;
+}
+
+/* Add runes representing a character in octal. */
+
+#define ADD_NEXT_OCTAL_RUNE_CHAR do				\
+{								\
+  if (add_failed || (add_failed = add_emchar_rune (data)))	\
+    {								\
+      struct prop_block pb;					\
+      if (!prop)						\
+	prop = Dynarr_new (prop_block);				\
+								\
+      pb.type = PROP_CHAR;					\
+      pb.data.p_char.ch = data->ch;				\
+      pb.data.p_char.cursor_type = data->cursor_type;		\
+      Dynarr_add (prop, pb);					\
+    }								\
+} while (0)
+
+static prop_block_dynarr *
+add_octal_runes (pos_data *data)
+{
+  prop_block_dynarr *prop, *add_failed;
+  Emchar orig_char = data->ch;
+  unsigned int orig_cursor_type = data->cursor_type;
+
+  /* Initialize */
+  prop = NULL;
+  add_failed = NULL;
+
+  if (data->start_col)
+    data->start_col--;
+
+  if (!data->start_col)
+    {
+    if (data->bi_start_col_enabled)
+      {
+	add_failed = add_hscroll_rune (data);
+      }
+    else
+      {
+	struct glyph_block gb;
+	struct window *w = XWINDOW (data->window);
+
+	gb.extent = Qnil;
+	gb.glyph = Voctal_escape_glyph;
+	add_failed =
+	  add_glyph_rune (data, &gb, BEGIN_GLYPHS, 1,
+			  GLYPH_CACHEL (w, OCT_ESC_GLYPH_INDEX));
+      }
+    }
+
+  /* We only propagate information if the glyph was partially
+     added. */
+  if (add_failed)
+    return add_failed;
+
+  data->cursor_type = IGNORE_CURSOR;
+
+  if (data->ch >= 0x100)
+    {
+      /* If the character is an extended Mule character, it could have
+	 up to 19 bits.  For the moment, we treat it as a seven-digit
+	 octal number.  This is not that pretty, but whatever. */
+      data->ch = (7 & (orig_char >> 18)) + '0';
+      ADD_NEXT_OCTAL_RUNE_CHAR;
+
+      data->ch = (7 & (orig_char >> 15)) + '0';
+      ADD_NEXT_OCTAL_RUNE_CHAR;
+
+      data->ch = (7 & (orig_char >> 12)) + '0';
+      ADD_NEXT_OCTAL_RUNE_CHAR;
+
+      data->ch = (7 & (orig_char >> 9)) + '0';
+      ADD_NEXT_OCTAL_RUNE_CHAR;
+    }
+
+  data->ch = (7 & (orig_char >> 6)) + '0';
+  ADD_NEXT_OCTAL_RUNE_CHAR;
+
+  data->ch = (7 & (orig_char >> 3)) + '0';
+  ADD_NEXT_OCTAL_RUNE_CHAR;
+
+  data->ch = (7 & orig_char) + '0';
+  ADD_NEXT_OCTAL_RUNE_CHAR;
+
+  data->cursor_type = orig_cursor_type;
+  return prop;
+}
+
+#undef ADD_NEXT_OCTAL_RUNE_CHAR
+
+/* Add runes representing a control character to a display block. */
+
+static prop_block_dynarr *
+add_control_char_runes (pos_data *data, struct buffer *b)
+{
+  if (!NILP (b->ctl_arrow))
+    {
+      prop_block_dynarr *prop;
+      Emchar orig_char = data->ch;
+      unsigned int old_cursor_type = data->cursor_type;
+
+      /* Initialize */
+      prop = NULL;
+
+      if (data->start_col)
+	data->start_col--;
+
+      if (!data->start_col)
+	{
+	  if (data->bi_start_col_enabled)
+	    {
+	      prop_block_dynarr *retval;
+
+	      retval = add_hscroll_rune (data);
+	      if (retval)
+		return retval;
+	    }
+	  else
+	    {
+	      struct glyph_block gb;
+	      struct window *w = XWINDOW (data->window);
+
+	      gb.extent = Qnil;
+	      gb.glyph = Vcontrol_arrow_glyph;
+
+	      /* We only propagate information if the glyph was partially
+		 added. */
+	      if (add_glyph_rune (data, &gb, BEGIN_GLYPHS, 1,
+				  GLYPH_CACHEL (w, CONTROL_GLYPH_INDEX)))
+		return ADD_FAILED;
+	    }
+	}
+
+      if (orig_char == 0177)
+	data->ch = '?';
+      else
+	data->ch = orig_char ^ 0100;
+      data->cursor_type = IGNORE_CURSOR;
+
+      if (add_emchar_rune (data))
+	{
+	  struct prop_block pb;
+	  if (!prop)
+	    prop = Dynarr_new (prop_block);
+
+	  pb.type = PROP_CHAR;
+	  pb.data.p_char.ch = data->ch;
+	  pb.data.p_char.cursor_type = data->cursor_type;
+	  Dynarr_add (prop, pb);
+	}
+
+      data->cursor_type = old_cursor_type;
+      return prop;
+    }
+  else
+    {
+      return add_octal_runes (data);
+    }
+}
+
+static prop_block_dynarr *
+add_disp_table_entry_runes_1 (pos_data *data, Lisp_Object entry)
+{
+  prop_block_dynarr *prop = NULL;
+
+  if (STRINGP (entry))
+    {
+      prop = add_bufbyte_string_runes (data,
+				       XSTRING_DATA   (entry),
+				       XSTRING_LENGTH (entry),
+				       0);
+    }
+  else if (GLYPHP (entry))
+    {
+      if (data->start_col)
+	data->start_col--;
+
+      if (!data->start_col && data->bi_start_col_enabled)
+	{
+	  prop = add_hscroll_rune (data);
+	}
+      else
+	{
+	  struct glyph_block gb;
+
+	  gb.glyph = entry;
+	  gb.extent = Qnil;
+	  prop = add_glyph_rune (data, &gb, BEGIN_GLYPHS, 0, 0);
+	}
+    }
+  else if (CHAR_OR_CHAR_INTP (entry))
+    {
+      data->ch = XCHAR_OR_CHAR_INT (entry);
+      prop = add_emchar_rune (data);
+    }
+  else if (CONSP (entry))
+    {
+      if (EQ (XCAR (entry), Qformat)
+	  && CONSP (XCDR (entry))
+	  && STRINGP (XCAR (XCDR (entry))))
+	{
+	  Lisp_Object format = XCAR (XCDR (entry));
+	  Bytind len = XSTRING_LENGTH (format);
+	  Bufbyte *src = XSTRING_DATA (format), *end = src + len;
+	  Bufbyte *result = alloca_array (Bufbyte, len);
+	  Bufbyte *dst = result;
+
+	  while (src < end)
+	    {
+	      Emchar c = charptr_emchar (src);
+	      INC_CHARPTR (src);
+	      if (c != '%' || src == end)
+		dst += set_charptr_emchar (dst, c);
+	      else
+		{
+		  c = charptr_emchar (src);
+		  INC_CHARPTR (src);
+		  switch (c)
+		    {
+		      /*case 'x':
+		      dst += long_to_string_base ((char *)dst, data->ch, 16);
+		      break;*/
+		    case '%':
+		      dst += set_charptr_emchar (dst, '%');
+		      break;
+		    }
+		}
+	    }
+	  prop = add_bufbyte_string_runes (data, result, dst - result, 0);
+	}
+    }
+
+  /* Else blow it off because someone added a bad entry and we don't
+     have any safe way of signaling an error. */
+  return prop;
+}
+
+/* Given a display table entry, call the appropriate functions to
+   display each element of the entry. */
+
+static prop_block_dynarr *
+add_disp_table_entry_runes (pos_data *data, Lisp_Object entry)
+{
+  prop_block_dynarr *prop = NULL;
+  if (VECTORP (entry))
+    {
+      struct Lisp_Vector *de = XVECTOR (entry);
+      EMACS_INT len = vector_length (de);
+      int elt;
+
+      for (elt = 0; elt < len; elt++)
+	{
+	  if (NILP (vector_data (de)[elt]))
+	    continue;
+	  else
+	    prop = add_disp_table_entry_runes_1 (data, vector_data (de)[elt]);
+	  /* Else blow it off because someone added a bad entry and we
+	     don't have any safe way of signaling an error.  Hey, this
+	     comment sounds familiar. */
+
+	  /* #### Still need to add any remaining elements to the
+             propagation information. */
+	  if (prop)
+	    return prop;
+	}
+    }
+  else
+    prop = add_disp_table_entry_runes_1 (data, entry);
+  return prop;
+}
+
+/* Add runes which were propagated from the previous line. */
+
+static prop_block_dynarr *
+add_propagation_runes (prop_block_dynarr **prop, pos_data *data)
+{
+  /* #### Remember to handle start_col parameter of data when the rest of
+     this is finished. */
+  /* #### Chuck -- I've redone this function a bit.  It looked like the
+     case of not all the propagation blocks being added was not handled
+     well. */
+  /* #### Chuck -- I also think the double indirection of PROP is kind
+     of bogus.  A cleaner solution is just to check for
+     Dynarr_length (prop) > 0. */
+  /* #### This function also doesn't even pay attention to ADD_FAILED!
+     This is seriously fucked!  Seven ####'s in 130 lines -- is that a
+     record? */
+  int elt;
+  prop_block_dynarr *add_failed;
+  Bytind bi_old_cursor_bufpos = data->bi_cursor_bufpos;
+  unsigned int old_cursor_type = data->cursor_type;
+
+  for (elt = 0; elt < Dynarr_length (*prop); elt++)
+    {
+      struct prop_block *pb = Dynarr_atp (*prop, elt);
+
+      switch (pb->type)
+	{
+	case PROP_CHAR:
+	  data->ch = pb->data.p_char.ch;
+	  data->bi_cursor_bufpos = pb->data.p_char.bi_cursor_bufpos;
+	  data->cursor_type = pb->data.p_char.cursor_type;
+	  add_failed = add_emchar_rune (data);
+
+	  if (add_failed)
+	    goto oops_no_more_space;
+	  break;
+	case PROP_STRING:
+	  if (pb->data.p_string.str)
+	    xfree (pb->data.p_string.str);
+	  /* #### bogus bogus -- this doesn't do anything!
+	     Should probably call add_bufbyte_string_runes(),
+	     once that function is fixed. */
+	  break;
+	case PROP_MINIBUF_PROMPT:
+	  {
+	    face_index old_findex = data->findex;
+	    Bytind bi_old_bufpos = data->bi_bufpos;
+
+	    data->findex = DEFAULT_INDEX;
+	    data->bi_bufpos = 0;
+	    data->cursor_type = NO_CURSOR;
+
+	    while (pb->data.p_string.len > 0)
+	      {
+		data->ch = charptr_emchar (pb->data.p_string.str);
+		add_failed = add_emchar_rune (data);
+
+		if (add_failed)
+		  {
+		    data->findex = old_findex;
+		    data->bi_bufpos = bi_old_bufpos;
+		    goto oops_no_more_space;
+		  }
+		else
+		  {
+		    /* Complicated equivalent of ptr++, len-- */
+		    Bufbyte *oldpos = pb->data.p_string.str;
+		    INC_CHARPTR (pb->data.p_string.str);
+		    pb->data.p_string.len -= pb->data.p_string.str - oldpos;
+		  }
+	      }
+
+	    data->findex = old_findex;
+	    /* ##### FIXME FIXME FIXME -- Upon successful return from
+	       this function, data->bi_bufpos is automatically incremented.
+	       However, we don't want that to happen if we were adding
+	       the minibuffer prompt. */
+	    {
+	      struct buffer *buf =
+		XBUFFER (WINDOW_BUFFER (XWINDOW (data->window)));
+	      /* #### Chuck fix this shit or I'm gonna scream! */
+	      if (bi_old_bufpos > BI_BUF_BEGV (buf))
+	        data->bi_bufpos = prev_bytind (buf, bi_old_bufpos);
+              else
+		/* #### is this correct?  Does anyone know?
+		   Does anyone care? Is this a cheesy hack or what? */
+	        data->bi_bufpos = BI_BUF_BEGV (buf) - 1;
+	    }
+	  }
+	  break;
+	case PROP_BLANK:
+	  {
+	    /* #### I think it's unnecessary and misleading to preserve
+	       the blank_width, as it implies that the value carries
+	       over from one rune to the next, which is wrong. */
+	    int old_width = data->blank_width;
+	    face_index old_findex = data->findex;
+
+	    data->findex = pb->data.p_blank.findex;
+	    data->blank_width = pb->data.p_blank.width;
+	    data->bi_cursor_bufpos = 0;
+	    data->cursor_type = IGNORE_CURSOR;
+
+	    if (data->pixpos + data->blank_width > data->max_pixpos)
+	      data->blank_width = data->max_pixpos - data->pixpos;
+
+	    /* We pass a bogus value of char_tab_width.  It shouldn't
+               matter because unless something is really screwed up
+               this call won't cause that arg to be used. */
+	    add_failed = add_blank_rune (data, XWINDOW (data->window), 0);
+
+	    /* This can happen in the case where we have a tab which
+               is wider than the window. */
+	    if (data->blank_width != pb->data.p_blank.width)
+	      {
+		pb->data.p_blank.width -= data->blank_width;
+		add_failed = ADD_FAILED;
+	      }
+
+	    data->findex = old_findex;
+	    data->blank_width = old_width;
+
+	    if (add_failed)
+	      goto oops_no_more_space;
+	  }
+	  break;
+	default:
+	  abort ();
+	}
+    }
+
+ oops_no_more_space:
+
+  data->bi_cursor_bufpos = bi_old_cursor_bufpos;
+  data->cursor_type = old_cursor_type;
+  if (elt < Dynarr_length (*prop))
+    {
+      Dynarr_delete_many (*prop, 0, elt);
+      return *prop;
+    }
+  else
+    {
+      Dynarr_free (*prop);
+      return NULL;
+    }
+}
+
+/* Add 'text layout glyphs at position POS_TYPE that are contained to
+   the display block, but add all other types to the appropriate list
+   of the display line.  They will be added later by different
+   routines. */
+
+static prop_block_dynarr *
+add_glyph_rune (pos_data *data, struct glyph_block *gb, int pos_type,
+		int allow_cursor, struct glyph_cachel *cachel)
+{
+  struct window *w = XWINDOW (data->window);
+
+  /* A nil extent indicates a special glyph (ex. truncator). */
+  if (NILP (gb->extent)
+      || (pos_type == BEGIN_GLYPHS &&
+	  extent_begin_glyph_layout (XEXTENT (gb->extent)) == GL_TEXT)
+      || (pos_type == END_GLYPHS &&
+	  extent_end_glyph_layout (XEXTENT (gb->extent)) == GL_TEXT))
+    {
+      struct rune rb;
+      int width;
+      int xoffset = 0;
+      int ascent, descent;
+      Lisp_Object baseline;
+      Lisp_Object face;
+
+      if (cachel)
+	width = cachel->width;
+      else
+	width = glyph_width (gb->glyph, Qnil, data->findex, data->window);
+
+      if (!width)
+	return NULL;
+
+      if (data->start_col || data->start_col_xoffset)
+	{
+	  prop_block_dynarr *retval;
+	  int glyph_char_width = width / space_width (w);
+
+	  /* If we still have not fully scrolled horizontally after
+             taking into account the width of the glyph, subtract its
+             width and return. */
+	  if (glyph_char_width < data->start_col)
+	    {
+	      data->start_col -= glyph_char_width;
+	      return NULL;
+	    }
+	  else if (glyph_char_width == data->start_col)
+	    width = 0;
+	  else
+	    {
+	      xoffset = space_width (w) * data->start_col;
+	      width -= xoffset;
+
+	      /* #### Can this happen? */
+	      if (width < 0)
+		width = 0;
+	    }
+
+	  data->start_col = 0;
+	  retval = add_hscroll_rune (data);
+
+	  /* Could be caused by the handling of the hscroll rune. */
+	  if (retval != NULL || !width)
+	    return retval;
+	}
+      else
+	xoffset = 0;
+
+      if (data->pixpos + width > data->max_pixpos)
+	{
+	  /* If this is the first object we are attempting to add to
+             the line then we ignore the horizontal_clip threshold.
+             Otherwise we will loop until the bottom of the window
+             continually failing to add this glyph because it is wider
+             than the window.  We could alternatively just completely
+             ignore the glyph and proceed from there but I think that
+             this is a better solution. */
+	  if (Dynarr_length (data->db->runes)
+	      && data->max_pixpos - data->pixpos < horizontal_clip)
+	    return ADD_FAILED;
+	  else
+	    width = data->max_pixpos - data->pixpos;
+	}
+
+      if (cachel)
+	{
+	  ascent = cachel->ascent;
+	  descent = cachel->descent;
+	}
+      else
+	{
+	  ascent = glyph_ascent (gb->glyph, Qnil, data->findex, data->window);
+	  descent = glyph_descent (gb->glyph, Qnil, data->findex,
+				   data->window);
+	}
+
+      baseline = glyph_baseline (gb->glyph, data->window);
+
+      if (glyph_contrib_p (gb->glyph, data->window))
+	{
+	  /* A pixmap that has not had a baseline explicitly set.  Its
+	     contribution will be determined later. */
+	  if (NILP (baseline))
+	    {
+	      int height = ascent + descent;
+	      data->max_pixmap_height = max (data->max_pixmap_height, height);
+	    }
+
+	  /* A string so determine contribution normally. */
+	  else if (EQ (baseline, Qt))
+	    {
+	      data->new_ascent = max (data->new_ascent, ascent);
+	      data->new_descent = max (data->new_descent, descent);
+	    }
+
+	  /* A pixmap with an explicitly set baseline.  We determine the
+	     contribution here. */
+	  else if (INTP (baseline))
+	    {
+	      int height = ascent + descent;
+	      int pix_ascent, pix_descent;
+
+	      pix_ascent = height * XINT (baseline) / 100;
+	      pix_descent = height - pix_ascent;
+
+	      data->new_ascent = max (data->new_ascent, pix_ascent);
+	      data->new_descent = max (data->new_descent, pix_descent);
+	    }
+
+	  /* Otherwise something is screwed up. */
+	  else
+	    abort ();
+	}
+
+      face = glyph_face (gb->glyph, data->window);
+      if (NILP (face))
+	rb.findex = data->findex;
+      else
+	rb.findex = get_builtin_face_cache_index (w, face);
+
+      rb.xpos = data->pixpos;
+      rb.width = width;
+      rb.bufpos = 0;			/* glyphs are never "at" anywhere */
+      if (data->bi_endpos)
+	/* #### is this necessary at all? */
+	rb.endpos = bytind_to_bufpos (XBUFFER (WINDOW_BUFFER (w)),
+				      data->bi_endpos);
+      else
+        rb.endpos = 0;
+      rb.type = RUNE_DGLYPH;
+      /* #### Ben sez: this is way bogus if the glyph is a string.
+	 You should not make the output routines have to cope with
+	 this.  The string could contain Mule characters, or non-
+	 printable characters, or characters to be passed through
+	 the display table, or non-character objects (when this gets
+	 implemented), etc.  Instead, this routine here should parse
+	 the string into a series of runes. */
+      rb.object.dglyph.glyph = gb->glyph;
+      rb.object.dglyph.extent = gb->extent;
+      rb.object.dglyph.xoffset = xoffset;
+
+      if (allow_cursor)
+	{
+	  rb.bufpos = bytind_to_bufpos (XBUFFER (WINDOW_BUFFER (w)),
+					data->bi_bufpos);
+
+	  if (data->cursor_type == CURSOR_ON)
+	    {
+	      if (data->bi_bufpos == data->bi_cursor_bufpos)
+		{
+		  rb.cursor_type = CURSOR_ON;
+		  data->cursor_x = Dynarr_length (data->db->runes);
+		}
+	      else
+		rb.cursor_type = CURSOR_OFF;
+	    }
+	  else if (data->cursor_type == NEXT_CURSOR)
+	    {
+	      rb.cursor_type = CURSOR_ON;
+	      data->cursor_x = Dynarr_length (data->db->runes);
+	      data->cursor_type = NO_CURSOR;
+	    }
+	  else if (data->cursor_type == IGNORE_CURSOR)
+	    rb.cursor_type = IGNORE_CURSOR;
+	  else if (data->cursor_type == NO_CURSOR)
+	    rb.cursor_type = NO_CURSOR;
+	  else
+	    rb.cursor_type = CURSOR_OFF;
+	}
+      else
+	rb.cursor_type = CURSOR_OFF;
+
+      Dynarr_add (data->db->runes, rb);
+      data->pixpos += width;
+
+      return NULL;
+    }
+  else
+    {
+      if (!NILP (glyph_face (gb->glyph, data->window)))
+	gb->findex =
+	  get_builtin_face_cache_index (w, glyph_face (gb->glyph,
+						       data->window));
+      else
+	gb->findex = data->findex;
+
+      if (pos_type == BEGIN_GLYPHS)
+	{
+	  if (!data->dl->left_glyphs)
+	    data->dl->left_glyphs = Dynarr_new (glyph_block);
+	  Dynarr_add (data->dl->left_glyphs, *gb);
+	  return NULL;
+	}
+      else if (pos_type == END_GLYPHS)
+	{
+	  if (!data->dl->right_glyphs)
+	    data->dl->right_glyphs = Dynarr_new (glyph_block);
+	  Dynarr_add (data->dl->right_glyphs, *gb);
+	  return NULL;
+	}
+      else
+	abort ();	/* there are no unknown types */
+    }
+
+  return NULL;	/* shut up compiler */
+}
+
+/* Add all glyphs at position POS_TYPE that are contained in the given
+   data. */
+
+static prop_block_dynarr *
+add_glyph_runes (pos_data *data, int pos_type)
+{
+  /* #### This still needs to handle the start_col parameter.  Duh, Chuck,
+     why didn't you just modify add_glyph_rune in the first place? */
+  int elt;
+  glyph_block_dynarr *glyph_arr = (pos_type == BEGIN_GLYPHS
+				   ? data->ef->begin_glyphs
+				   : data->ef->end_glyphs);
+  prop_block_dynarr *prop;
+
+  for (elt = 0; elt < Dynarr_length (glyph_arr); elt++)
+    {
+      prop = add_glyph_rune (data, Dynarr_atp (glyph_arr, elt), pos_type, 0,
+			     0);
+
+      if (prop)
+	{
+	  /* #### Add some propagation information. */
+	  return prop;
+	}
+    }
+
+  Dynarr_reset (glyph_arr);
+
+  return NULL;
+}
+
+/* Given a position for a buffer in a window, ensure that the given
+   display line DL accurately represents the text on a line starting
+   at the given position.
+
+   NOTE NOTE NOTE NOTE: This function works with and returns Bytinds.
+   You must do appropriate conversion. */
+
+static Bytind
+create_text_block (struct window *w, struct display_line *dl,
+		   Bytind bi_start_pos, prop_block_dynarr **prop,
+		   int type)
+{
+  struct frame *f = XFRAME (w->frame);
+  struct buffer *b = XBUFFER (w->buffer);
+  struct device *d = XDEVICE (f->device);
+
+  pos_data data;
+
+  /* Don't display anything in the minibuffer if this window is not on
+     a selected frame.  We consider all other windows to be active
+     minibuffers as it simplifies the coding. */
+  int active_minibuffer = (!MINI_WINDOW_P (w) ||
+			   (f == device_selected_frame (d)) ||
+			   is_surrogate_for_selected_frame (f));
+
+  int truncate_win = window_truncation_on (w);
+  int end_glyph_width;
+
+  /* If the buffer's value of selective_display is an integer then
+     only lines that start with less than selective_display columns of
+     space will be displayed.  If selective_display is t then all text
+     after a ^M is invisible. */
+  int selective = (INTP (b->selective_display)
+		   ? XINT (b->selective_display)
+		   : ((!NILP (b->selective_display) ? -1 : 0)));
+
+  /* The variable ctl-arrow allows the user to specify what characters
+     can actually be displayed and which octal should be used for.
+     #### This variable should probably have some rethought done to
+     it.
+
+     #### It would also be really nice if you could specify that
+     the characters come out in hex instead of in octal.  Mule
+     does that by adding a ctl-hexa variable similar to ctl-arrow,
+     but that's bogus -- we need a more general solution.  I
+     think you need to extend the concept of display tables
+     into a more general conversion mechanism.  Ideally you
+     could specify a Lisp function that converts characters,
+     but this violates the Second Golden Rule and besides would
+     make things way way way way slow.
+
+     So instead, we extend the display-table concept, which was
+     historically limited to 256-byte vectors, to one of the
+     following:
+
+     a) A 256-entry vector, for backward compatibility;
+     b) char-table, mapping characters to values;
+     c) range-table, mapping ranges of characters to values;
+     d) a list of the above.
+
+     The (d) option allows you to specify multiple display tables
+     instead of just one.  Each display table can specify conversions
+     for some characters and leave others unchanged.  The way the
+     character gets displayed is determined by the first display table
+     with a binding for that character.  This way, you could call a
+     function `enable-hex-display' that adds a hex display-table to
+     the list of display tables for the current buffer.
+
+     #### ...not yet implemented...  Also, we extend the concept of
+     "mapping" to include a printf-like spec.  Thus you can make all
+     extended characters show up as hex with a display table like
+     this:
+
+         #s(range-table data ((256 524288) (format "%x")))
+
+     Since more than one display table is possible, you have
+     great flexibility in mapping ranges of characters.  */
+  Emchar printable_min = (CHAR_OR_CHAR_INTP (b->ctl_arrow)
+			  ? XCHAR_OR_CHAR_INT (b->ctl_arrow)
+			  : ((EQ (b->ctl_arrow, Qt) || EQ (b->ctl_arrow, Qnil))
+			     ? 255 : 160));
+
+  Lisp_Object face_dt, window_dt;
+
+  /* The text display block for this display line. */
+  struct display_block *db = get_display_block_from_line (dl, TEXT);
+
+  /* The first time through the main loop we need to force the glyph
+     data to be updated. */
+  int initial = 1;
+
+  /* Apparently the new extent_fragment_update returns an end position
+     equal to the position passed in if there are no more runs to be
+     displayed. */
+  int no_more_frags = 0;
+
+  Lisp_Object synch_minibuffers_value =
+    symbol_value_in_buffer (Qsynchronize_minibuffers, w->buffer);
+
+  dl->used_prop_data = 0;
+  dl->num_chars = 0;
+
+  xzero (data);
+  data.ef = extent_fragment_new (w->buffer, f);
+
+  /* These values are used by all of the rune addition routines.  We add
+     them to this structure for ease of passing. */
+  data.d = d;
+  XSETWINDOW (data.window, w);
+  data.string = Qnil;
+  data.db = db;
+  data.dl = dl;
+
+  data.bi_bufpos = bi_start_pos;
+  data.pixpos = dl->bounds.left_in;
+  data.last_charset = Qunbound;
+  data.last_findex = DEFAULT_INDEX;
+  data.result_str = Qnil;
+
+  /* Set the right boundary adjusting it to take into account any end
+     glyph.  Save the width of the end glyph for later use. */
+  data.max_pixpos = dl->bounds.right_in;
+  if (truncate_win)
+    end_glyph_width = GLYPH_CACHEL_WIDTH (w, TRUN_GLYPH_INDEX);
+  else
+    end_glyph_width = GLYPH_CACHEL_WIDTH (w, CONT_GLYPH_INDEX);
+  data.max_pixpos -= end_glyph_width;
+
+  if (cursor_in_echo_area && MINI_WINDOW_P (w) && echo_area_active (f))
+    {
+      data.bi_cursor_bufpos = BI_BUF_ZV (b);
+      data.cursor_type = CURSOR_ON;
+    }
+  else if (MINI_WINDOW_P (w) && !active_minibuffer)
+    data.cursor_type = NO_CURSOR;
+  else if (w == XWINDOW (FRAME_SELECTED_WINDOW (f)) &&
+	   EQ(DEVICE_CONSOLE(d), Vselected_console) &&
+	   d == XDEVICE(CONSOLE_SELECTED_DEVICE(XCONSOLE(DEVICE_CONSOLE(d))))&&
+	   f == XFRAME(DEVICE_SELECTED_FRAME(d)))
+    {
+      data.bi_cursor_bufpos = BI_BUF_PT (b);
+      data.cursor_type = CURSOR_ON;
+    }
+  else if (w == XWINDOW (FRAME_SELECTED_WINDOW (f)))
+    {
+      data.bi_cursor_bufpos = bi_marker_position (w->pointm[type]);
+      data.cursor_type = CURSOR_ON;
+    }
+  else
+    data.cursor_type = NO_CURSOR;
+  data.cursor_x = -1;
+
+  data.start_col = w->hscroll;
+  data.start_col_xoffset = w->left_xoffset;
+  data.bi_start_col_enabled = (w->hscroll ? bi_start_pos : 0);
+  data.hscroll_glyph_width_adjust = 0;
+
+  /* We regenerate the line from the very beginning. */
+  Dynarr_reset (db->runes);
+
+  /* Why is this less than or equal and not just less than?  If the
+     starting position is already equal to the maximum we can't add
+     anything else, right?  Wrong.  We might still have a newline to
+     add.  A newline can use the room allocated for an end glyph since
+     if we add it we know we aren't going to be adding any end
+     glyph. */
+
+  /* #### Chuck -- I think this condition should be while (1).
+     Otherwise if (e.g.) there is one begin-glyph and one end-glyph
+     and the begin-glyph ends exactly at the end of the window, the
+     end-glyph and text might not be displayed.  while (1) ensures
+     that the loop terminates only when either (a) there is
+     propagation data or (b) the end-of-line or end-of-buffer is hit.
+
+     #### Also I think you need to ensure that the operation
+     "add begin glyphs; add end glyphs; add text" is atomic and
+     can't get interrupted in the middle.  If you run off the end
+     of the line during that operation, then you keep accumulating
+     propagation data until you're done.  Otherwise, if the (e.g.)
+     there's a begin glyph at a particular position and attempting
+     to display that glyph results in window-end being hit and
+     propagation data being generated, then the character at that
+     position won't be displayed.
+
+     #### See also the comment after the end of this loop, below.
+     */
+  while (data.pixpos <= data.max_pixpos
+	 && (active_minibuffer || !NILP (synch_minibuffers_value)))
+    {
+      /* #### This check probably should not be necessary. */
+      if (data.bi_bufpos > BI_BUF_ZV (b))
+	{
+	  /* #### urk!  More of this lossage! */
+	  data.bi_bufpos--;
+	  goto done;
+	}
+
+      /* If selective display was an integer and we aren't working on
+         a continuation line then find the next line we are actually
+         supposed to display. */
+      if (selective > 0
+	  && (data.bi_bufpos == BI_BUF_BEGV (b)
+	      || BUF_FETCH_CHAR (b, prev_bytind (b, data.bi_bufpos)) == '\n'))
+	{
+	  while (bi_spaces_at_point (b, data.bi_bufpos) >= selective)
+	    {
+	      data.bi_bufpos =
+		bi_find_next_newline_no_quit (b, data.bi_bufpos, 1);
+	      if (data.bi_bufpos >= BI_BUF_ZV (b))
+		{
+		  data.bi_bufpos = BI_BUF_ZV (b);
+		  goto done;
+		}
+	    }
+	}
+
+      /* Check for face changes. */
+      if (initial || (!no_more_frags && data.bi_bufpos == data.ef->end))
+	{
+	  /* Now compute the face and begin/end-glyph information. */
+	  data.findex =
+	    /* Remember that the extent-fragment routines deal in Bytind's. */
+	    extent_fragment_update (w, data.ef, data.bi_bufpos);
+
+	  get_display_tables (w, data.findex, &face_dt, &window_dt);
+
+	  if (data.bi_bufpos == data.ef->end)
+	    no_more_frags = 1;
+	}
+      initial = 0;
+
+      /* Determine what is next to be displayed.  We first handle any
+         glyphs returned by glyphs_at_bufpos.  If there are no glyphs to
+         display then we determine what to do based on the character at the
+         current buffer position. */
+
+      /* If the current position is covered by an invisible extent, do
+         nothing (except maybe add some ellipses).
+
+	 #### The behavior of begin and end-glyphs at the edge of an
+	 invisible extent should be investigated further.  This is
+	 fairly low priority though. */
+      if (data.ef->invisible)
+	{
+	  /* #### Chuck, perhaps you could look at this code?  I don't
+	     really know what I'm doing. */
+	  if (*prop)
+	    {
+	      Dynarr_free (*prop);
+	      *prop = 0;
+	    }
+
+	  /* The extent fragment code only sets this when we should
+	     really display the ellipses.  It makes sure the ellipses
+	     don't get displayed more than once in a row. */
+	  if (data.ef->invisible_ellipses)
+	    {
+	      struct glyph_block gb;
+
+	      data.ef->invisible_ellipses_already_displayed = 1;
+	      data.ef->invisible_ellipses = 0;
+	      gb.extent = Qnil;
+	      gb.glyph = Vinvisible_text_glyph;
+	      *prop = add_glyph_rune (&data, &gb, BEGIN_GLYPHS, 0,
+				      GLYPH_CACHEL (w, INVIS_GLYPH_INDEX));
+	      /* Perhaps they shouldn't propagate if the very next thing
+		 is to display a newline (for compatibility with
+		 selective-display-ellipses)?  Maybe that's too
+		 abstruse. */
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* If point is in an invisible region we place it on the
+             next visible character. */
+	  if (data.cursor_type == CURSOR_ON
+	      && data.bi_bufpos == data.bi_cursor_bufpos)
+	    {
+	      data.cursor_type = NEXT_CURSOR;
+	    }
+
+	  /* #### What if we we're dealing with a display table? */
+	  if (data.start_col)
+	    data.start_col--;
+
+	  if (data.bi_bufpos == BI_BUF_ZV (b))
+	    goto done;
+	  else
+	    INC_BYTIND (b, data.bi_bufpos);
+	}
+
+      /* If there is propagation data, then it represents the current
+         buffer position being displayed.  Add them and advance the
+         position counter.  This might also add the minibuffer
+         prompt. */
+      else if (*prop)
+	{
+	  dl->used_prop_data = 1;
+	  *prop = add_propagation_runes (prop, &data);
+
+	  if (*prop)
+	    goto done;	/* gee, a really narrow window */
+	  else if (data.bi_bufpos == BI_BUF_ZV (b))
+	    goto done;
+	  else if (data.bi_bufpos < BI_BUF_BEGV (b))
+	    /* #### urk urk urk! Aborts are not very fun! Fix this please! */
+	    data.bi_bufpos = BI_BUF_BEGV (b);
+	  else
+	    INC_BYTIND (b, data.bi_bufpos);
+	}
+
+      /* If there are end glyphs, add them to the line.  These are
+	 the end glyphs for the previous run of text.  We add them
+	 here rather than doing them at the end of handling the
+	 previous run so that glyphs at the beginning and end of
+	 a line are handled correctly. */
+      else if (Dynarr_length (data.ef->end_glyphs) > 0)
+	{
+	  *prop = add_glyph_runes (&data, END_GLYPHS);
+	  if (*prop)
+	    goto done;
+	}
+
+      /* If there are begin glyphs, add them to the line. */
+      else if (Dynarr_length (data.ef->begin_glyphs) > 0)
+	{
+	  *prop = add_glyph_runes (&data, BEGIN_GLYPHS);
+	  if (*prop)
+	    goto done;
+	}
+
+      /* If at end-of-buffer, we've already processed begin and
+	 end-glyphs at this point and there's no text to process,
+	 so we're done. */
+      else if (data.bi_bufpos == BI_BUF_ZV (b))
+	goto done;
+
+      else
+	{
+	  Lisp_Object entry = Qnil;
+	  /* Get the character at the current buffer position. */
+	  data.ch = BI_BUF_FETCH_CHAR (b, data.bi_bufpos);
+	  if (!NILP (face_dt) || !NILP (window_dt))
+	    entry = display_table_entry (data.ch, face_dt, window_dt);
+
+	  /* If there is a display table entry for it, hand it off to
+             add_disp_table_entry_runes and let it worry about it. */
+	  if (!NILP (entry) && !EQ (entry, make_char (data.ch)))
+	    {
+	      *prop = add_disp_table_entry_runes (&data, entry);
+
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* Check if we have hit a newline character.  If so, add a marker
+             to the line and end this loop. */
+	  else if (data.ch == '\n')
+	    {
+	      /* We aren't going to be adding an end glyph so give its
+                 space back in order to make sure that the cursor can
+                 fit. */
+	      data.max_pixpos += end_glyph_width;
+
+	      if (selective > 0
+		  && (bi_spaces_at_point
+		      (b, next_bytind (b, data.bi_bufpos))
+		      >= selective))
+		{
+		  if (!NILP (b->selective_display_ellipses))
+		    {
+		      struct glyph_block gb;
+
+		      gb.extent = Qnil;
+		      gb.glyph = Vinvisible_text_glyph;
+		      add_glyph_rune (&data, &gb, BEGIN_GLYPHS, 0,
+				      GLYPH_CACHEL (w, INVIS_GLYPH_INDEX));
+		    }
+		  else
+		    {
+		      /* Cheesy, cheesy, cheesy.  We mark the end of the
+			 line with a special "character rune" whose width
+			 is the EOL cursor width and whose character is
+			 the non-printing character '\n'. */
+		      data.blank_width = DEVMETH (d, eol_cursor_width, ());
+		      *prop = add_emchar_rune (&data);
+		    }
+
+		  /* We need to set data.bi_bufpos to the start of the
+                     next visible region in order to make this line
+                     appear to contain all of the invisible area.
+                     Otherwise, the line cache won't work
+                     correctly. */
+		  INC_BYTIND (b, data.bi_bufpos);
+		  while (bi_spaces_at_point (b, data.bi_bufpos) >= selective)
+		    {
+		      data.bi_bufpos =
+			bi_find_next_newline_no_quit (b, data.bi_bufpos, 1);
+		      if (data.bi_bufpos >= BI_BUF_ZV (b))
+			{
+			  data.bi_bufpos = BI_BUF_ZV (b);
+			  break;
+			}
+		    }
+		  if (BI_BUF_FETCH_CHAR
+		      (b, prev_bytind (b, data.bi_bufpos)) == '\n')
+		    DEC_BYTIND (b, data.bi_bufpos);
+		}
+	      else
+		{
+		  data.blank_width = DEVMETH (d, eol_cursor_width, ());
+		  *prop = add_emchar_rune (&data);
+		}
+
+	      goto done;
+	    }
+
+	  /* If the current character is ^M, and selective display is
+             enabled, then add the invisible-text-glyph if
+             selective-display-ellipses is set.  In any case, this
+             line is done. */
+	  else if (data.ch == (('M' & 037)) && selective == -1)
+	    {
+	      Bytind bi_next_bufpos;
+
+	      /* Find the buffer position at the end of the line. */
+	      bi_next_bufpos =
+		bi_find_next_newline_no_quit (b, data.bi_bufpos, 1);
+	      if (BI_BUF_FETCH_CHAR (b, prev_bytind (b, bi_next_bufpos))
+		  == '\n')
+		DEC_BYTIND (b, bi_next_bufpos);
+
+	      /* If the cursor is somewhere in the elided text make
+                 sure that the cursor gets drawn appropriately. */
+	      if (data.cursor_type == CURSOR_ON
+		  && (data.bi_cursor_bufpos >= data.bi_bufpos &&
+		      data.bi_cursor_bufpos < bi_next_bufpos))
+		{
+		    data.cursor_type = NEXT_CURSOR;
+		}
+
+	      /* We won't be adding a truncation or continuation glyph
+                 so give up the room allocated for them. */
+	      data.max_pixpos += end_glyph_width;
+
+	      if (!NILP (b->selective_display_ellipses))
+		{
+		  /* We don't propagate anything from the invisible
+                     text glyph if it fails to fit.  This is
+                     intentional. */
+		  struct glyph_block gb;
+
+		  gb.extent = Qnil;
+		  gb.glyph = Vinvisible_text_glyph;
+		  add_glyph_rune (&data, &gb, BEGIN_GLYPHS, 1,
+				  GLYPH_CACHEL (w, INVIS_GLYPH_INDEX));
+		}
+
+	      /* Set the buffer position to the end of the line.  We
+                 need to do this before potentially adding a newline
+                 so that the cursor flag will get set correctly (if
+                 needed). */
+	      data.bi_bufpos = bi_next_bufpos;
+
+	      if (NILP (b->selective_display_ellipses)
+		  || data.bi_cursor_bufpos == bi_next_bufpos)
+		{
+		  /* We have to at least add a newline character so
+                     that the cursor shows up properly. */
+		  data.ch = '\n';
+		  data.blank_width = DEVMETH (d, eol_cursor_width, ());
+		  data.findex = DEFAULT_INDEX;
+		  data.start_col = 0;
+		  data.start_col_xoffset = 0;
+		  data.bi_start_col_enabled = 0;
+
+		  add_emchar_rune (&data);
+		}
+
+	      /* This had better be a newline but doing it this way
+                 we'll see obvious incorrect results if it isn't.  No
+                 need to abort here. */
+	      data.ch = BI_BUF_FETCH_CHAR (b, data.bi_bufpos);
+
+	      goto done;
+	    }
+
+	  /* If the current character is considered to be printable, then
+             just add it. */
+	  else if (data.ch >= printable_min)
+	    {
+	      *prop = add_emchar_rune (&data);
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* If the current character is a tab, determine the next tab
+             starting position and add a blank rune which extends from the
+             current pixel position to that starting position. */
+	  else if (data.ch == '\t')
+	    {
+	      int tab_start_pixpos = data.pixpos;
+	      int next_tab_start;
+	      int char_tab_width;
+	      int prop_width = 0;
+
+	      if (data.start_col > 1)
+		tab_start_pixpos -= (space_width (w) * (data.start_col - 1)) 
+		  + data.start_col_xoffset;
+
+	      next_tab_start =
+		next_tab_position (w, tab_start_pixpos,
+				   dl->bounds.left_in +
+				   data.hscroll_glyph_width_adjust);
+	      if (next_tab_start > data.max_pixpos)
+		{
+		  prop_width = next_tab_start - data.max_pixpos;
+		  next_tab_start = data.max_pixpos;
+		}
+	      data.blank_width = next_tab_start - data.pixpos;
+	      char_tab_width =
+		(next_tab_start - tab_start_pixpos) / space_width (w);
+
+	      *prop = add_blank_rune (&data, w, char_tab_width);
+
+	      /* add_blank_rune is only supposed to be called with
+                 sizes guaranteed to fit in the available space. */
+	      assert (!(*prop));
+
+	      if (prop_width)
+		{
+		  struct prop_block pb;
+		  *prop = Dynarr_new (prop_block);
+
+		  pb.type = PROP_BLANK;
+		  pb.data.p_blank.width = prop_width;
+		  pb.data.p_blank.findex = data.findex;
+		  Dynarr_add (*prop, pb);
+
+		  goto done;
+		}
+	    }
+
+	  /* If character is a control character, pass it off to
+             add_control_char_runes.
+
+	     The is_*() routines have undefined results on
+	     arguments outside of the range [-1, 255].  (This
+	     often bites people who carelessly use `char' instead
+	     of `unsigned char'.)
+	     */
+	  else if (data.ch < 0x100 && iscntrl ((Bufbyte) data.ch))
+	    {
+	      *prop = add_control_char_runes (&data, b);
+
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* If the character is above the ASCII range and we have not
+             already handled it, then print it as an octal number. */
+	  else if (data.ch >= 0200)
+	    {
+	      *prop = add_octal_runes (&data);
+
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* Assume the current character is considered to be printable,
+             then just add it. */
+	  else
+	    {
+	      *prop = add_emchar_rune (&data);
+	      if (*prop)
+		goto done;
+	    }
+
+	  INC_BYTIND (b, data.bi_bufpos);
+	}
+    }
+
+done:
+
+  /* Determine the starting point of the next line if we did not hit the
+     end of the buffer. */
+  if (data.bi_bufpos < BI_BUF_ZV (b)
+      && (active_minibuffer || !NILP (synch_minibuffers_value)))
+    {
+      /* #### This check is not correct.  If the line terminated
+	 due to a begin-glyph or end-glyph hitting window-end, then
+	 data.ch will not point to the character at data.bi_bufpos.  If
+	 you make the two changes mentioned at the top of this loop,
+	 you should be able to say '(if (*prop))'.  That should also
+	 make it possible to eliminate the data.bi_bufpos < BI_BUF_ZV (b)
+	 check. */
+
+      /* The common case is that the line ended because we hit a newline.
+         In that case, the next character is just the next buffer
+         position. */
+      if (data.ch == '\n')
+	{
+	  /* If data.start_col_enabled is still true, then the window is
+             scrolled far enough so that nothing on this line is visible.
+             We need to stick a truncation glyph at the beginning of the
+             line in that case unless the line is completely blank. */
+	  if (data.bi_start_col_enabled)
+	    {
+	      if (data.cursor_type == CURSOR_ON)
+		{
+		  if (data.bi_cursor_bufpos >= bi_start_pos
+		      && data.bi_cursor_bufpos <= data.bi_bufpos)
+		    data.bi_cursor_bufpos = data.bi_bufpos;
+		}
+	      data.findex = DEFAULT_INDEX;
+	      data.start_col = 0;
+	      data.bi_start_col_enabled = 0;
+
+	      if (data.bi_bufpos != bi_start_pos)
+		{
+		  struct glyph_block gb;
+
+		  gb.extent = Qnil;
+		  gb.glyph = Vhscroll_glyph;
+		  add_glyph_rune (&data, &gb, BEGIN_GLYPHS, 0,
+				  GLYPH_CACHEL (w, HSCROLL_GLYPH_INDEX));
+		}
+	      else
+		{
+		  /* This duplicates code down below to add a newline to
+                     the end of an otherwise empty line.*/
+		  data.ch = '\n';
+		  data.blank_width = DEVMETH (d, eol_cursor_width, ());
+
+		  add_emchar_rune (&data);
+		}
+	    }
+
+	  INC_BYTIND (b, data.bi_bufpos);
+	}
+
+      /* Otherwise we have a buffer line which cannot fit on one display
+         line. */
+      else
+	{
+	  struct glyph_block gb;
+	  struct glyph_cachel *cachel;
+
+	  /* If the line is to be truncated then we actually have to look
+             for the next newline.  We also add the end-of-line glyph which
+             we know will fit because we adjusted the right border before
+             we starting laying out the line. */
+	  data.max_pixpos += end_glyph_width;
+	  data.findex = DEFAULT_INDEX;
+	  gb.extent = Qnil;
+
+	  if (truncate_win)
+	    {
+	      Bytind bi_pos;
+
+	      /* Now find the start of the next line. */
+	      bi_pos = bi_find_next_newline_no_quit (b, data.bi_bufpos, 1);
+
+	      /* If the cursor is past the truncation line then we
+                 make it appear on the truncation glyph.  If we've hit
+                 the end of the buffer then we also make the cursor
+                 appear unless eob is immediately preceded by a
+                 newline.  In that case the cursor should actually
+                 appear on the next line. */
+	      if (data.cursor_type == CURSOR_ON
+		  && data.bi_cursor_bufpos >= data.bi_bufpos
+		  && (data.bi_cursor_bufpos < bi_pos ||
+		      (bi_pos == BI_BUF_ZV (b)
+		       && (bi_pos == BI_BUF_BEGV (b)
+			   || (BI_BUF_FETCH_CHAR (b, prev_bytind (b, bi_pos))
+			       != '\n')))))
+		data.bi_cursor_bufpos = bi_pos;
+	      else
+		data.cursor_type = NO_CURSOR;
+
+	      data.bi_bufpos = bi_pos;
+	      gb.glyph = Vtruncation_glyph;
+	      cachel = GLYPH_CACHEL (w, TRUN_GLYPH_INDEX);
+	    }
+	  else
+	    {
+	      /* The cursor can never be on the continuation glyph. */
+	      data.cursor_type = NO_CURSOR;
+
+	      /* data.bi_bufpos is already at the start of the next line. */
+
+	      gb.glyph = Vcontinuation_glyph;
+	      cachel = GLYPH_CACHEL (w, CONT_GLYPH_INDEX);
+	    }
+
+	  add_glyph_rune (&data, &gb, BEGIN_GLYPHS, 1, cachel);
+
+	  if (truncate_win && data.bi_bufpos == BI_BUF_ZV (b)
+	      && BI_BUF_FETCH_CHAR (b, prev_bytind (b, BI_BUF_ZV (b))) != '\n')
+	    /* #### Damn this losing shit. */
+	    data.bi_bufpos++;
+	}
+    }
+  else if ((active_minibuffer || !NILP (synch_minibuffers_value))
+	   && (!echo_area_active (f) || data.bi_bufpos == BI_BUF_ZV (b)))
+    {
+      /* We need to add a marker to the end of the line since there is no
+         newline character in order for the cursor to get drawn.  We label
+         it as a newline so that it gets handled correctly by the
+         whitespace routines below. */
+
+      data.ch = '\n';
+      data.blank_width = DEVMETH (d, eol_cursor_width, ());
+      data.findex = DEFAULT_INDEX;
+      data.start_col = 0;
+      data.start_col_xoffset = 0;
+      data.bi_start_col_enabled = 0;
+
+      data.max_pixpos += data.blank_width;
+      add_emchar_rune (&data);
+      data.max_pixpos -= data.blank_width;
+
+      /* #### urk!  Chuck, this shit is bad news.  Going around
+	 manipulating invalid positions is guaranteed to result in
+	 trouble sooner or later. */
+      data.bi_bufpos = BI_BUF_ZV (b) + 1;
+    }
+
+  /* Calculate left whitespace boundary. */
+  {
+    int elt = 0;
+
+    /* Whitespace past a newline is considered right whitespace. */
+    while (elt < Dynarr_length (db->runes))
+      {
+	struct rune *rb = Dynarr_atp (db->runes, elt);
+
+	if ((rb->type == RUNE_CHAR && rb->object.chr.ch == ' ')
+	    || rb->type == RUNE_BLANK)
+	  {
+	    dl->bounds.left_white += rb->width;
+	    elt++;
+	  }
+	else
+	  elt = Dynarr_length (db->runes);
+      }
+  }
+
+  /* Calculate right whitespace boundary. */
+  {
+    int elt = Dynarr_length (db->runes) - 1;
+    int done = 0;
+
+    while (!done && elt >= 0)
+      {
+	struct rune *rb = Dynarr_atp (db->runes, elt);
+
+	if (!(rb->type == RUNE_CHAR && rb->object.chr.ch < 0x100
+	    && isspace (rb->object.chr.ch))
+	    && !rb->type == RUNE_BLANK)
+	  {
+	    dl->bounds.right_white = rb->xpos + rb->width;
+	    done = 1;
+	  }
+
+	elt--;
+
+      }
+
+    /* The line is blank so everything is considered to be right
+       whitespace. */
+    if (!done)
+      dl->bounds.right_white = dl->bounds.left_in;
+  }
+
+  /* Set the display blocks bounds. */
+  db->start_pos = dl->bounds.left_in;
+  if (Dynarr_length (db->runes))
+    {
+      struct rune *rb = Dynarr_atp (db->runes, Dynarr_length (db->runes) - 1);
+
+      db->end_pos = rb->xpos + rb->width;
+    }
+  else
+    db->end_pos = dl->bounds.right_white;
+
+  /* update line height parameters */
+  if (!data.new_ascent && !data.new_descent)
+    {
+      /* We've got a blank line so initialize these values from the default
+         face. */
+      default_face_font_info (data.window, &data.new_ascent,
+			      &data.new_descent, 0, 0, 0);
+    }
+
+  if (data.max_pixmap_height)
+    {
+      int height = data.new_ascent + data.new_descent;
+      int pix_ascent, pix_descent;
+
+      pix_descent = data.max_pixmap_height * data.new_descent / height;
+      pix_ascent = data.max_pixmap_height - pix_descent;
+
+      data.new_ascent = max (data.new_ascent, pix_ascent);
+      data.new_descent = max (data.new_descent, pix_descent);
+    }
+
+  dl->ascent = data.new_ascent;
+  dl->descent = data.new_descent;
+
+  {
+    unsigned short ascent = (unsigned short) XINT (w->minimum_line_ascent);
+
+    if (dl->ascent < ascent)
+      dl->ascent = ascent;
+  }
+  {
+    unsigned short descent = (unsigned short) XINT (w->minimum_line_descent);
+
+    if (dl->descent < descent)
+      dl->descent = descent;
+  }
+
+  dl->cursor_elt = data.cursor_x;
+  /* #### lossage lossage lossage! Fix this shit! */
+  if (data.bi_bufpos > BI_BUF_ZV (b))
+    dl->end_bufpos = BUF_ZV (b);
+  else
+    dl->end_bufpos = bytind_to_bufpos (b, data.bi_bufpos) - 1;
+  if (truncate_win)
+    data.dl->num_chars = column_at_point (b, dl->end_bufpos, 0);
+  else
+    /* This doesn't correctly take into account tabs and control
+       characters but if the window isn't being truncated then this
+       value isn't going to end up being used anyhow. */
+    data.dl->num_chars = dl->end_bufpos - dl->bufpos;
+
+  /* #### handle horizontally scrolled line with text none of which
+     was actually laid out. */
+
+  /* #### handle any remainder of overlay arrow */
+
+  if (*prop == ADD_FAILED)
+    *prop = NULL;
+
+  if (truncate_win && *prop)
+    {
+      Dynarr_free (*prop);
+      *prop = NULL;
+    }
+
+  extent_fragment_delete (data.ef);
+
+  /* #### If we started at EOB, then make sure we return a value past
+     it so that regenerate_window will exit properly.  This is bogus.
+     The main loop should get fixed so that it isn't necessary to call
+     this function if we are already at EOB. */
+
+  if (data.bi_bufpos == BI_BUF_ZV (b) && bi_start_pos == BI_BUF_ZV (b))
+    return data.bi_bufpos + 1; /* Yuck! */
+  else
+    return data.bi_bufpos;
+}
+
+/* Display the overlay arrow at the beginning of the given line. */
+
+static int
+create_overlay_glyph_block (struct window *w, struct display_line *dl)
+{
+  struct frame *f = XFRAME (w->frame);
+  struct device *d = XDEVICE (f->device);
+  pos_data data;
+
+  /* If Voverlay_arrow_string isn't valid then just fail silently. */
+  if (!STRINGP (Voverlay_arrow_string) && !GLYPHP (Voverlay_arrow_string))
+    return 0;
+
+  xzero (data);
+  data.ef = NULL;
+  data.d = d;
+  XSETWINDOW (data.window, w);
+  data.db = get_display_block_from_line (dl, OVERWRITE);
+  data.dl = dl;
+  data.pixpos = dl->bounds.left_in;
+  data.max_pixpos = dl->bounds.right_in;
+  data.cursor_type = NO_CURSOR;
+  data.cursor_x = -1;
+  data.findex = DEFAULT_INDEX;
+  data.last_charset = Qunbound;
+  data.last_findex = DEFAULT_INDEX;
+  data.result_str = Qnil;
+  data.string = Qnil;
+
+  Dynarr_reset (data.db->runes);
+
+  if (STRINGP (Voverlay_arrow_string))
+    {
+      add_bufbyte_string_runes
+	(&data,
+	 XSTRING_DATA   (Voverlay_arrow_string),
+	 XSTRING_LENGTH (Voverlay_arrow_string),
+	 1);
+    }
+  else if (GLYPHP (Voverlay_arrow_string))
+    {
+      struct glyph_block gb;
+
+      gb.glyph = Voverlay_arrow_string;
+      gb.extent = Qnil;
+      add_glyph_rune (&data, &gb, BEGIN_GLYPHS, 0, 0);
+    }
+
+  if (data.max_pixmap_height)
+    {
+      int height = data.new_ascent + data.new_descent;
+      int pix_ascent, pix_descent;
+
+      pix_descent = data.max_pixmap_height * data.new_descent / height;
+      pix_ascent = data.max_pixmap_height - pix_descent;
+
+      data.new_ascent = max (data.new_ascent, pix_ascent);
+      data.new_descent = max (data.new_descent, pix_descent);
+    }
+
+  dl->ascent = data.new_ascent;
+  dl->descent = data.new_descent;
+
+  data.db->start_pos = dl->bounds.left_in;
+  data.db->end_pos = data.pixpos;
+
+  return data.pixpos - dl->bounds.left_in;
+}
+
+/* Add a type of glyph to a margin display block. */
+
+static int
+add_margin_runes (struct display_line *dl, struct display_block *db, int start,
+		  int count, enum glyph_layout layout, int side, Lisp_Object window)
+{
+  glyph_block_dynarr *gbd = (side == LEFT_GLYPHS
+			     ? dl->left_glyphs
+			     : dl->right_glyphs);
+  int elt, end;
+  int xpos = start;
+  int reverse;
+
+  if ((layout == GL_WHITESPACE && side == LEFT_GLYPHS)
+      || (layout == GL_INSIDE_MARGIN && side == RIGHT_GLYPHS))
+    {
+      reverse = 1;
+      elt = Dynarr_length (gbd) - 1;
+      end = 0;
+    }
+  else
+    {
+      reverse = 0;
+      elt = 0;
+      end = Dynarr_length (gbd);
+    }
+
+  while (count && ((!reverse && elt < end) || (reverse && elt >= end)))
+    {
+      struct glyph_block *gb = Dynarr_atp (gbd, elt);
+
+      if (NILP (gb->extent))
+	abort ();	/* these should have been handled in add_glyph_rune */
+
+      if (gb->active &&
+	  ((side == LEFT_GLYPHS &&
+	    extent_begin_glyph_layout (XEXTENT (gb->extent)) == layout)
+	   || (side == RIGHT_GLYPHS &&
+	       extent_end_glyph_layout (XEXTENT (gb->extent)) == layout)))
+	{
+	  struct rune rb;
+
+	  rb.width = gb->width;
+	  rb.findex = gb->findex;
+	  rb.xpos = xpos;
+	  rb.bufpos = -1;
+	  rb.endpos = 0;
+	  rb.type = RUNE_DGLYPH;
+	  rb.object.dglyph.glyph = gb->glyph;
+	  rb.object.dglyph.extent = gb->extent;
+	  rb.object.dglyph.xoffset = 0;
+	  rb.cursor_type = CURSOR_OFF;
+
+	  Dynarr_add (db->runes, rb);
+	  xpos += rb.width;
+	  count--;
+	  gb->active = 0;
+
+	  if (glyph_contrib_p (gb->glyph, window))
+	    {
+	      unsigned short ascent, descent;
+	      Lisp_Object baseline = glyph_baseline (gb->glyph, window);
+
+	      ascent = glyph_ascent (gb->glyph, Qnil, gb->findex, window);
+	      descent = glyph_descent (gb->glyph, Qnil, gb->findex, window);
+
+	      /* A pixmap that has not had a baseline explicitly set.
+                 We use the existing ascent / descent ratio of the
+                 line. */
+	      if (NILP (baseline))
+		{
+		  int gheight = ascent + descent;
+		  int line_height = dl->ascent + dl->descent;
+		  int pix_ascent, pix_descent;
+
+		  pix_descent = (int) (gheight * dl->descent) / line_height;
+		  pix_ascent = gheight - pix_descent;
+
+		  dl->ascent = max ((int) dl->ascent, pix_ascent);
+		  dl->descent = max ((int) dl->descent, pix_descent);
+		}
+
+	      /* A string so determine contribution normally. */
+	      else if (EQ (baseline, Qt))
+		{
+		  dl->ascent = max (dl->ascent, ascent);
+		  dl->descent = max (dl->descent, descent);
+		}
+
+	      /* A pixmap with an explicitly set baseline.  We determine the
+		 contribution here. */
+	      else if (INTP (baseline))
+		{
+		  int height = ascent + descent;
+		  int pix_ascent, pix_descent;
+
+		  pix_ascent = height * XINT (baseline) / 100;
+		  pix_descent = height - pix_ascent;
+
+		  dl->ascent = max ((int) dl->ascent, pix_ascent);
+		  dl->descent = max ((int) dl->descent, pix_descent);
+		}
+
+	      /* Otherwise something is screwed up. */
+	      else
+		abort ();
+	    }
+	}
+
+      (reverse ? elt-- : elt++);
+    }
+
+  return xpos;
+}
+
+/* Add a blank to a margin display block. */
+
+static void
+add_margin_blank (struct display_line *dl, struct display_block *db,
+		  struct window *w, int xpos, int width, int side)
+{
+  struct rune rb;
+
+  rb.findex = (side == LEFT_GLYPHS
+	       ? get_builtin_face_cache_index (w, Vleft_margin_face)
+	       : get_builtin_face_cache_index (w, Vright_margin_face));
+  rb.xpos = xpos;
+  rb.width = width;
+  rb.bufpos = -1;
+  rb.endpos = 0;
+  rb.type = RUNE_BLANK;
+  rb.cursor_type = CURSOR_OFF;
+
+  Dynarr_add (db->runes, rb);
+}
+
+/* Display glyphs in the left outside margin, left inside margin and
+   left whitespace area. */
+
+static void
+create_left_glyph_block (struct window *w, struct display_line *dl,
+			 int overlay_width)
+{
+  Lisp_Object window;
+
+  int use_overflow = (NILP (w->use_left_overflow) ? 0 : 1);
+  int elt, end_xpos;
+  int out_end, in_out_start, in_in_end, white_out_start, white_in_start;
+  int out_cnt, in_out_cnt, in_in_cnt, white_out_cnt, white_in_cnt;
+  int left_in_start = dl->bounds.left_in;
+  int left_in_end = dl->bounds.left_in + overlay_width;
+
+  struct display_block *odb, *idb;
+
+  XSETWINDOW (window, w);
+
+  /* We have to add the glyphs to the line in the order outside,
+     inside, whitespace.  However the precedence dictates that we
+     determine how many will fit in the reverse order. */
+
+  /* Determine how many whitespace glyphs we can display and where
+     they should start. */
+  white_in_start = dl->bounds.left_white;
+  white_out_start = left_in_start;
+  white_out_cnt = white_in_cnt = 0;
+  elt = 0;
+
+  while (elt < Dynarr_length (dl->left_glyphs))
+    {
+      struct glyph_block *gb = Dynarr_atp (dl->left_glyphs, elt);
+
+      if (NILP (gb->extent))
+	abort ();	/* these should have been handled in add_glyph_rune */
+
+      if (extent_begin_glyph_layout (XEXTENT (gb->extent)) == GL_WHITESPACE)
+	{
+	  int width;
+
+	  width = glyph_width (gb->glyph, Qnil, gb->findex, window);
+
+	  if (white_in_start - width >= left_in_end)
+	    {
+	      white_in_cnt++;
+	      white_in_start -= width;
+	      gb->width = width;
+	      gb->active = 1;
+	    }
+	  else if (use_overflow
+		   && (white_out_start - width > dl->bounds.left_out))
+	    {
+	      white_out_cnt++;
+	      white_out_start -= width;
+	      gb->width = width;
+	      gb->active = 1;
+	    }
+	  else
+	    gb->active = 0;
+	}
+
+      elt++;
+    }
+
+  /* Determine how many inside margin glyphs we can display and where
+     they should start.  The inside margin glyphs get whatever space
+     is left after the whitespace glyphs have been displayed.  These
+     are tricky to calculate since if we decide to use the overflow
+     area we basically have to start over.  So for these we build up a
+     list of just the inside margin glyphs and manipulate it to
+     determine the needed info. */
+  {
+    glyph_block_dynarr *ib;
+    int avail_in, avail_out;
+    int done = 0;
+    int marker = 0;
+    int used_in, used_out;
+
+    elt = 0;
+    used_in = used_out = 0;
+    ib = Dynarr_new (glyph_block);
+    while (elt < Dynarr_length (dl->left_glyphs))
+      {
+	struct glyph_block *gb = Dynarr_atp (dl->left_glyphs, elt);
+
+	if (NILP (gb->extent))
+	  abort ();	/* these should have been handled in add_glyph_rune */
+
+	if (extent_begin_glyph_layout (XEXTENT (gb->extent)) ==
+	    GL_INSIDE_MARGIN)
+	  {
+	    gb->width = glyph_width (gb->glyph, Qnil, gb->findex, window);
+	    used_in += gb->width;
+	    Dynarr_add (ib, *gb);
+	  }
+
+	elt++;
+      }
+
+    if (white_out_cnt)
+      avail_in = 0;
+    else
+      {
+	avail_in = white_in_start - left_in_end;
+	if (avail_in < 0)
+	  avail_in = 0;
+      }
+
+    if (!use_overflow)
+      avail_out = 0;
+    else
+      avail_out = white_out_start - dl->bounds.left_out;
+
+    marker = 0;
+    while (!done && marker < Dynarr_length (ib))
+      {
+	int width = Dynarr_atp (ib, marker)->width;
+
+	/* If everything now fits in the available inside margin
+           space, we're done. */
+	if (used_in <= avail_in)
+	  done = 1;
+	else
+	  {
+	    /* Otherwise see if we have room to move a glyph to the
+               outside. */
+	    if (used_out + width <= avail_out)
+	      {
+		used_out += width;
+		used_in -= width;
+	      }
+	    else
+	      done = 1;
+	  }
+
+	if (!done)
+	  marker++;
+      }
+
+    /* At this point we now know that everything from marker on goes in
+       the inside margin and everything before it goes in the outside
+       margin.  The stuff going into the outside margin is guaranteed
+       to fit, but we may have to trim some stuff from the inside. */
+
+    in_in_end = left_in_end;
+    in_out_start = white_out_start;
+    in_out_cnt = in_in_cnt = 0;
+
+    Dynarr_free (ib);
+    elt = 0;
+    while (elt < Dynarr_length (dl->left_glyphs))
+      {
+	struct glyph_block *gb = Dynarr_atp (dl->left_glyphs, elt);
+
+	if (NILP (gb->extent))
+	  abort ();	/* these should have been handled in add_glyph_rune */
+
+	if (extent_begin_glyph_layout (XEXTENT (gb->extent)) ==
+	    GL_INSIDE_MARGIN)
+	  {
+	    int width = glyph_width (gb->glyph, Qnil, gb->findex, window);
+
+	    if (used_out)
+	      {
+		in_out_cnt++;
+		in_out_start -= width;
+		gb->width = width;
+		gb->active = 1;
+		used_out -= width;
+	      }
+	    else if (in_in_end + width < white_in_start)
+	      {
+		in_in_cnt++;
+		in_in_end += width;
+		gb->width = width;
+		gb->active = 1;
+	      }
+	    else
+	      gb->active = 0;
+	  }
+
+	elt++;
+      }
+  }
+
+  /* Determine how many outside margin glyphs we can display.  They
+     always start at the left outside margin and can only use the
+     outside margin space. */
+  out_end = dl->bounds.left_out;
+  out_cnt = 0;
+  elt = 0;
+
+  while (elt < Dynarr_length (dl->left_glyphs))
+    {
+      struct glyph_block *gb = Dynarr_atp (dl->left_glyphs, elt);
+
+      if (NILP (gb->extent))
+	abort ();	/* these should have been handled in add_glyph_rune */
+
+      if (extent_begin_glyph_layout (XEXTENT (gb->extent)) ==
+	  GL_OUTSIDE_MARGIN)
+	{
+	  int width = glyph_width (gb->glyph, Qnil, gb->findex, window);
+
+	  if (out_end + width <= in_out_start)
+	    {
+	      out_cnt++;
+	      out_end += width;
+	      gb->width = width;
+	      gb->active = 1;
+	    }
+	  else
+	    gb->active = 0;
+	}
+
+      elt++;
+    }
+
+  /* Now that we know where everything goes, we add the glyphs as
+     runes to the appropriate display blocks. */
+  if (out_cnt || in_out_cnt || white_out_cnt)
+    {
+      odb = get_display_block_from_line (dl, LEFT_OUTSIDE_MARGIN);
+      odb->start_pos = dl->bounds.left_out;
+      /* #### We should stop adding a blank to account for the space
+         between the end of the glyphs and the margin and instead set
+         this accordingly. */
+      odb->end_pos = dl->bounds.left_in;
+      Dynarr_reset (odb->runes);
+    }
+  else
+    odb = 0;
+
+  if (in_in_cnt || white_in_cnt)
+    {
+      idb = get_display_block_from_line (dl, LEFT_INSIDE_MARGIN);
+      idb->start_pos = dl->bounds.left_in;
+      /* #### See above comment for odb->end_pos */
+      idb->end_pos = dl->bounds.left_white;
+      Dynarr_reset (idb->runes);
+    }
+  else
+    idb = 0;
+
+  /* First add the outside margin glyphs. */
+  if (out_cnt)
+    end_xpos = add_margin_runes (dl, odb, dl->bounds.left_out, out_cnt,
+				 GL_OUTSIDE_MARGIN, LEFT_GLYPHS, window);
+  else
+    end_xpos = dl->bounds.left_out;
+
+  /* There may be blank space between the outside margin glyphs and
+     the inside margin glyphs.  If so, add a blank. */
+  if (in_out_cnt && (in_out_start - end_xpos))
+    {
+      add_margin_blank (dl, odb, w, end_xpos, in_out_start - end_xpos,
+			LEFT_GLYPHS);
+    }
+
+  /* Next add the inside margin glyphs which are actually in the
+     outside margin. */
+  if (in_out_cnt)
+    {
+      end_xpos = add_margin_runes (dl, odb, in_out_start, in_out_cnt,
+				   GL_INSIDE_MARGIN, LEFT_GLYPHS, window);
+    }
+
+  /* If we didn't add any inside margin glyphs to the outside margin,
+     but are adding whitespace glyphs, then we need to add a blank
+     here. */
+  if (!in_out_cnt && white_out_cnt && (white_out_start - end_xpos))
+    {
+      add_margin_blank (dl, odb, w, end_xpos, white_out_start - end_xpos,
+			LEFT_GLYPHS);
+    }
+
+  /* Next add the whitespace margin glyphs which are actually in the
+     outside margin. */
+  if (white_out_cnt)
+    {
+      end_xpos = add_margin_runes (dl, odb, white_out_start, white_out_cnt,
+				   GL_WHITESPACE, LEFT_GLYPHS, window);
+    }
+
+  /* We take care of clearing between the end of the glyphs and the
+     start of the inside margin for lines which have glyphs.  */
+  if (odb && (left_in_start - end_xpos))
+    {
+      add_margin_blank (dl, odb, w, end_xpos, left_in_start - end_xpos,
+			LEFT_GLYPHS);
+    }
+
+  /* Next add the inside margin glyphs which are actually in the
+     inside margin. */
+  if (in_in_cnt)
+    {
+      end_xpos = add_margin_runes (dl, idb, left_in_end, in_in_cnt,
+				   GL_INSIDE_MARGIN, LEFT_GLYPHS, window);
+    }
+  else
+    end_xpos = left_in_end;
+
+  /* Make sure that the area between the end of the inside margin
+     glyphs and the whitespace glyphs is cleared. */
+  if (idb && (white_in_start - end_xpos > 0))
+    {
+      add_margin_blank (dl, idb, w, end_xpos, white_in_start - end_xpos,
+			LEFT_GLYPHS);
+    }
+
+  /* Next add the whitespace margin glyphs which are actually in the
+     inside margin. */
+  if (white_in_cnt)
+    {
+      add_margin_runes (dl, idb, white_in_start, white_in_cnt, GL_WHITESPACE,
+			LEFT_GLYPHS, window);
+    }
+
+  /* Whitespace glyphs always end right next to the text block so
+     there is nothing we have to make sure is cleared after them. */
+}
+
+/* Display glyphs in the right outside margin, right inside margin and
+   right whitespace area. */
+
+static void
+create_right_glyph_block (struct window *w, struct display_line *dl)
+{
+  Lisp_Object window;
+
+  int use_overflow = (NILP (w->use_right_overflow) ? 0 : 1);
+  int elt, end_xpos;
+  int out_start, in_out_end, in_in_start, white_out_end, white_in_end;
+  int out_cnt, in_out_cnt, in_in_cnt, white_out_cnt, white_in_cnt;
+
+  struct display_block *odb, *idb;
+
+  XSETWINDOW (window, w);
+
+  /* We have to add the glyphs to the line in the order outside,
+     inside, whitespace.  However the precedence dictates that we
+     determine how many will fit in the reverse order. */
+
+  /* Determine how many whitespace glyphs we can display and where
+     they should start. */
+  white_in_end = dl->bounds.right_white;
+  white_out_end = dl->bounds.right_in;
+  white_out_cnt = white_in_cnt = 0;
+  elt = 0;
+
+  while (elt < Dynarr_length (dl->right_glyphs))
+    {
+      struct glyph_block *gb = Dynarr_atp (dl->right_glyphs, elt);
+
+      if (NILP (gb->extent))
+	abort ();	/* these should have been handled in add_glyph_rune */
+
+      if (extent_end_glyph_layout (XEXTENT (gb->extent)) == GL_WHITESPACE)
+	{
+	  int width = glyph_width (gb->glyph, Qnil, gb->findex, window);
+
+	  if (white_in_end + width <= dl->bounds.right_in)
+	    {
+	      white_in_cnt++;
+	      white_in_end += width;
+	      gb->width = width;
+	      gb->active = 1;
+	    }
+	  else if (use_overflow
+		   && (white_out_end + width <= dl->bounds.right_out))
+	    {
+	      white_out_cnt++;
+	      white_out_end += width;
+	      gb->width = width;
+	      gb->active = 1;
+	    }
+	  else
+	    gb->active = 0;
+	}
+
+      elt++;
+    }
+
+  /* Determine how many inside margin glyphs we can display and where
+     they should start.  The inside margin glyphs get whatever space
+     is left after the whitespace glyphs have been displayed.  These
+     are tricky to calculate since if we decide to use the overflow
+     area we basically have to start over.  So for these we build up a
+     list of just the inside margin glyphs and manipulate it to
+     determine the needed info. */
+  {
+    glyph_block_dynarr *ib;
+    int avail_in, avail_out;
+    int done = 0;
+    int marker = 0;
+    int used_in, used_out;
+
+    elt = 0;
+    used_in = used_out = 0;
+    ib = Dynarr_new (glyph_block);
+    while (elt < Dynarr_length (dl->right_glyphs))
+      {
+	struct glyph_block *gb = Dynarr_atp (dl->right_glyphs, elt);
+
+	if (NILP (gb->extent))
+	  abort ();	/* these should have been handled in add_glyph_rune */
+
+	if (extent_end_glyph_layout (XEXTENT (gb->extent)) == GL_INSIDE_MARGIN)
+	  {
+	    gb->width = glyph_width (gb->glyph, Qnil, gb->findex, window);
+	    used_in += gb->width;
+	    Dynarr_add (ib, *gb);
+	  }
+
+	elt++;
+      }
+
+    if (white_out_cnt)
+      avail_in = 0;
+    else
+      avail_in = dl->bounds.right_in - white_in_end;
+
+    if (!use_overflow)
+      avail_out = 0;
+    else
+      avail_out = dl->bounds.right_out - white_out_end;
+
+    marker = 0;
+    while (!done && marker < Dynarr_length (ib))
+      {
+	int width = Dynarr_atp (ib, marker)->width;
+
+	/* If everything now fits in the available inside margin
+           space, we're done. */
+	if (used_in <= avail_in)
+	  done = 1;
+	else
+	  {
+	    /* Otherwise see if we have room to move a glyph to the
+               outside. */
+	    if (used_out + width <= avail_out)
+	      {
+		used_out += width;
+		used_in -= width;
+	      }
+	    else
+	      done = 1;
+	  }
+
+	if (!done)
+	  marker++;
+      }
+
+    /* At this point we now know that everything from marker on goes in
+       the inside margin and everything before it goes in the outside
+       margin.  The stuff going into the outside margin is guaranteed
+       to fit, but we may have to trim some stuff from the inside. */
+
+    in_in_start = dl->bounds.right_in;
+    in_out_end = dl->bounds.right_in;
+    in_out_cnt = in_in_cnt = 0;
+
+    Dynarr_free (ib);
+    elt = 0;
+    while (elt < Dynarr_length (dl->right_glyphs))
+      {
+	struct glyph_block *gb = Dynarr_atp (dl->right_glyphs, elt);
+
+	if (NILP (gb->extent))
+	  abort ();	/* these should have been handled in add_glyph_rune */
+
+	if (extent_end_glyph_layout (XEXTENT (gb->extent)) == GL_INSIDE_MARGIN)
+	  {
+	    int width = glyph_width (gb->glyph, Qnil, gb->findex, window);
+
+	    if (used_out)
+	      {
+		in_out_cnt++;
+		in_out_end += width;
+		gb->width = width;
+		gb->active = 1;
+		used_out -= width;
+	      }
+	    else if (in_in_start - width >= white_in_end)
+	      {
+		in_in_cnt++;
+		in_in_start -= width;
+		gb->width = width;
+		gb->active = 1;
+	      }
+	    else
+	      gb->active = 0;
+	  }
+
+	elt++;
+      }
+  }
+
+  /* Determine how many outside margin glyphs we can display.  They
+     always start at the right outside margin and can only use the
+     outside margin space. */
+  out_start = dl->bounds.right_out;
+  out_cnt = 0;
+  elt = 0;
+
+  while (elt < Dynarr_length (dl->right_glyphs))
+    {
+      struct glyph_block *gb = Dynarr_atp (dl->right_glyphs, elt);
+
+      if (NILP (gb->extent))
+	abort ();	/* these should have been handled in add_glyph_rune */
+
+      if (extent_end_glyph_layout (XEXTENT (gb->extent)) == GL_OUTSIDE_MARGIN)
+	{
+	  int width = glyph_width (gb->glyph, Qnil, gb->findex, window);
+
+	  if (out_start - width >= in_out_end)
+	    {
+	      out_cnt++;
+	      out_start -= width;
+	      gb->width = width;
+	      gb->active = 1;
+	    }
+	  else
+	    gb->active = 0;
+	}
+
+      elt++;
+    }
+
+  /* Now that we now where everything goes, we add the glyphs as runes
+     to the appropriate display blocks. */
+  if (out_cnt || in_out_cnt || white_out_cnt)
+    {
+      odb = get_display_block_from_line (dl, RIGHT_OUTSIDE_MARGIN);
+      /* #### See comments before odb->start_pos init in
+         create_left_glyph_block */
+      odb->start_pos = dl->bounds.right_in;
+      odb->end_pos = dl->bounds.right_out;
+      Dynarr_reset (odb->runes);
+    }
+  else
+    odb = 0;
+
+  if (in_in_cnt || white_in_cnt)
+    {
+      idb = get_display_block_from_line (dl, RIGHT_INSIDE_MARGIN);
+      idb->start_pos = dl->bounds.right_white;
+      /* #### See comments before odb->start_pos init in
+         create_left_glyph_block */
+      idb->end_pos = dl->bounds.right_in;
+      Dynarr_reset (idb->runes);
+    }
+  else
+    idb = 0;
+
+  /* First add the whitespace margin glyphs which are actually in the
+     inside margin. */
+  if (white_in_cnt)
+    {
+      end_xpos = add_margin_runes (dl, idb, dl->bounds.right_white,
+				   white_in_cnt, GL_WHITESPACE, RIGHT_GLYPHS,
+				   window);
+    }
+  else
+    end_xpos = dl->bounds.right_white;
+
+  /* Make sure that the area between the end of the whitespace glyphs
+     and the inside margin glyphs is cleared. */
+  if (in_in_cnt && (in_in_start - end_xpos))
+    {
+      add_margin_blank (dl, idb, w, end_xpos, in_in_start - end_xpos,
+			RIGHT_GLYPHS);
+    }
+
+  /* Next add the inside margin glyphs which are actually in the
+     inside margin. */
+  if (in_in_cnt)
+    {
+      end_xpos = add_margin_runes (dl, idb, in_in_start, in_in_cnt,
+				   GL_INSIDE_MARGIN, RIGHT_GLYPHS, window);
+    }
+
+  /* If we didn't add any inside margin glyphs then make sure the rest
+     of the inside margin area gets cleared. */
+  if (idb && (dl->bounds.right_in - end_xpos))
+    {
+      add_margin_blank (dl, idb, w, end_xpos, dl->bounds.right_in - end_xpos,
+			RIGHT_GLYPHS);
+    }
+
+  /* Next add any whitespace glyphs in the outside margin. */
+  if (white_out_cnt)
+    {
+      end_xpos = add_margin_runes (dl, odb, dl->bounds.right_in, white_out_cnt,
+				   GL_WHITESPACE, RIGHT_GLYPHS, window);
+    }
+  else
+    end_xpos = dl->bounds.right_in;
+
+  /* Next add any inside margin glyphs in the outside margin. */
+  if (in_out_cnt)
+    {
+      end_xpos = add_margin_runes (dl, odb, end_xpos, in_out_cnt,
+				   GL_INSIDE_MARGIN, RIGHT_GLYPHS, window);
+    }
+
+  /* There may be space between any whitespace or inside margin glyphs
+     in the outside margin and the actual outside margin glyphs. */
+  if (odb && (out_start - end_xpos))
+    {
+      add_margin_blank (dl, odb, w, end_xpos, out_start - end_xpos,
+			RIGHT_GLYPHS);
+    }
+
+  /* Finally, add the outside margin glyphs. */
+  if (out_cnt)
+    {
+      add_margin_runes (dl, odb, out_start, out_cnt, GL_OUTSIDE_MARGIN,
+			RIGHT_GLYPHS, window);
+    }
+}
+
+
+/***************************************************************************/
+/*									   */
+/*                            modeline routines                            */
+/*									   */
+/***************************************************************************/
+
+/* Ensure that the given display line DL accurately represents the
+   modeline for the given window. */
+
+static void
+generate_modeline (struct window *w, struct display_line *dl, int type)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  struct frame *f = XFRAME (w->frame);
+  struct device *d = XDEVICE (f->device);
+
+  /* Unlike display line and rune pointers, this one can't change underneath
+     our feet. */
+  struct display_block *db = get_display_block_from_line (dl, TEXT);
+  int max_pixpos, min_pixpos, ypos_adj;
+  Lisp_Object font_inst;
+
+  /* This will actually determine incorrect inside boundaries for the
+     modeline since it ignores the margins.  However being aware of this fact
+     we never use those values anywhere so it doesn't matter. */
+  dl->bounds = calculate_display_line_boundaries (w, 1);
+
+  /* We are generating a modeline. */
+  dl->modeline = 1;
+  dl->cursor_elt = -1;
+
+  /* Reset the runes on the modeline. */
+  Dynarr_reset (db->runes);
+
+  if (!WINDOW_HAS_MODELINE_P (w))
+    {
+      struct rune rb;
+
+      /* If there is a horizontal scrollbar, don't add anything. */
+      if (window_scrollbar_height (w))
+	return;
+
+      dl->ascent = DEVMETH (d, divider_height, ());
+      dl->descent = 0;
+      /* The modeline is at the bottom of the gutters. */
+      dl->ypos = WINDOW_BOTTOM (w);
+
+      /* adjust for the bottom gutter */
+      if (window_is_lowest (w))
+	dl->ypos -= FRAME_BOTTOM_GUTTER_BOUNDS (f);
+
+      rb.findex = MODELINE_INDEX;
+      rb.xpos = dl->bounds.left_out;
+      rb.width = dl->bounds.right_out - dl->bounds.left_out;
+      rb.bufpos = 0;
+      rb.endpos = 0;
+      rb.type = RUNE_HLINE;
+      rb.object.hline.thickness = 1;
+      rb.object.hline.yoffset = 0;
+      rb.cursor_type = NO_CURSOR;
+
+      if (!EQ (Qzero, w->modeline_shadow_thickness)
+	  && FRAME_WIN_P (f))
+	{
+	  int shadow_thickness = MODELINE_SHADOW_THICKNESS (w);
+
+	  dl->ypos -= shadow_thickness;
+	  rb.xpos += shadow_thickness;
+	  rb.width -= 2 * shadow_thickness;
+	}
+
+      Dynarr_add (db->runes, rb);
+      return;
+    }
+
+  /* !!#### not right; needs to compute the max height of
+     all the charsets */
+  font_inst = WINDOW_FACE_CACHEL_FONT (w, MODELINE_INDEX, Vcharset_ascii);
+
+  dl->ascent = XFONT_INSTANCE (font_inst)->ascent;
+  dl->descent = XFONT_INSTANCE (font_inst)->descent;
+
+  min_pixpos = dl->bounds.left_out;
+  max_pixpos = dl->bounds.right_out;
+
+  if (!EQ (Qzero, w->modeline_shadow_thickness) && FRAME_WIN_P (f))
+    {
+      int shadow_thickness = MODELINE_SHADOW_THICKNESS (w);
+
+      ypos_adj = shadow_thickness;
+      min_pixpos += shadow_thickness;
+      max_pixpos -= shadow_thickness;
+    }
+  else
+    ypos_adj = 0;
+
+  generate_formatted_string_db (b->modeline_format,
+				b->generated_modeline_string, w, dl, db,
+				MODELINE_INDEX, min_pixpos, max_pixpos, type);
+
+  /* The modeline is at the bottom of the gutters.  We have to wait to
+     set this until we've generated the modeline in order to account
+     for any embedded faces. */
+  dl->ypos = WINDOW_BOTTOM (w) - dl->descent - ypos_adj;
+  /* adjust for the bottom gutter */
+  if (window_is_lowest (w))
+    dl->ypos -= FRAME_BOTTOM_GUTTER_BOUNDS (f);
+}
+
+static void
+generate_formatted_string_db (Lisp_Object format_str, Lisp_Object result_str,
+                              struct window *w, struct display_line *dl,
+                              struct display_block *db, face_index findex,
+                              int min_pixpos, int max_pixpos, int type)
+{
+  struct frame *f = XFRAME (w->frame);
+  struct device *d = XDEVICE (f->device);
+
+  pos_data data;
+  int c_pixpos;
+
+  xzero (data);
+  data.d = d;
+  data.db = db;
+  data.dl = dl;
+  data.findex = findex;
+  data.pixpos = min_pixpos;
+  data.max_pixpos = max_pixpos;
+  data.cursor_type = NO_CURSOR;
+  data.last_charset = Qunbound;
+  data.last_findex = DEFAULT_INDEX;
+  data.result_str = result_str;
+  data.is_modeline = 1;
+  data.string = Qnil;
+  XSETWINDOW (data.window, w);
+
+  Dynarr_reset (formatted_string_extent_dynarr);
+  Dynarr_reset (formatted_string_extent_start_dynarr);
+  Dynarr_reset (formatted_string_extent_end_dynarr);
+
+  /* This recursively builds up the modeline. */
+  generate_fstring_runes (w, &data, 0, 0, -1, format_str, 0,
+                          max_pixpos - min_pixpos, findex, type);
+
+  if (Dynarr_length (db->runes))
+    {
+      struct rune *rb =
+        Dynarr_atp (db->runes, Dynarr_length (db->runes) - 1);
+      c_pixpos = rb->xpos + rb->width;
+    }
+  else
+    c_pixpos = min_pixpos;
+
+  /* If we don't reach the right side of the window, add a blank rune
+     to make up the difference.  This usually only occurs if the
+     modeline face is using a proportional width font or a fixed width
+     font of a different size from the default face font. */
+
+  if (c_pixpos < max_pixpos)
+    {
+      data.pixpos = c_pixpos;
+      data.blank_width = max_pixpos - data.pixpos;
+
+      add_blank_rune (&data, NULL, 0);
+    }
+
+  /* Now create the result string and frob the extents into it. */
+  if (!NILP (result_str))
+    {
+      int elt;
+      Bytecount len;
+      Bufbyte *strdata;
+      struct buffer *buf = XBUFFER (WINDOW_BUFFER (w));
+
+      detach_all_extents (result_str);
+      resize_string (XSTRING (result_str), -1,
+                     data.bytepos - XSTRING_LENGTH (result_str));
+
+      strdata = XSTRING_DATA (result_str);
+
+      for (elt = 0, len = 0; elt < Dynarr_length (db->runes); elt++)
+        {
+          if (Dynarr_atp (db->runes, elt)->type == RUNE_CHAR)
+            {
+              len += (set_charptr_emchar
+                      (strdata + len, Dynarr_atp (db->runes,
+                                                  elt)->object.chr.ch));
+            }
+        }
+
+      for (elt = 0; elt < Dynarr_length (formatted_string_extent_dynarr);
+           elt++)
+        {
+          Lisp_Object extent = Qnil;
+          Lisp_Object child;
+
+          XSETEXTENT (extent, Dynarr_at (formatted_string_extent_dynarr, elt));
+          child = Fgethash (extent, buf->modeline_extent_table, Qnil);
+          if (NILP (child))
+            {
+              child = Fmake_extent (Qnil, Qnil, result_str);
+              Fputhash (extent, child, buf->modeline_extent_table);
+            }
+          Fset_extent_parent (child, extent);
+          set_extent_endpoints
+            (XEXTENT (child),
+             Dynarr_at (formatted_string_extent_start_dynarr, elt),
+             Dynarr_at (formatted_string_extent_end_dynarr, elt),
+             result_str);
+        }
+    }
+}
+
+static Charcount
+add_string_to_fstring_db_runes (pos_data *data, CONST Bufbyte *str,
+                                Charcount pos, Charcount min_pos, Charcount max_pos)
+{
+  /* This function has been Mule-ized. */
+  Charcount end;
+  CONST Bufbyte *cur_pos = str;
+  struct display_block *db = data->db;
+
+  data->blank_width = space_width (XWINDOW (data->window));
+  while (Dynarr_length (db->runes) < pos)
+    add_blank_rune (data, NULL, 0);
+
+  end = (Dynarr_length (db->runes) +
+         bytecount_to_charcount (str, strlen ((CONST char *) str)));
+  if (max_pos != -1)
+    end = min (max_pos, end);
+
+  while (pos < end && *cur_pos)
+    {
+      CONST Bufbyte *old_cur_pos = cur_pos;
+      int succeeded;
+
+      data->ch = charptr_emchar (cur_pos);
+      succeeded = (add_emchar_rune (data) != ADD_FAILED);
+      INC_CHARPTR (cur_pos);
+      if (succeeded)
+        {
+          pos++;
+          data->modeline_charpos++;
+          data->bytepos += cur_pos - old_cur_pos;
+        }
+    }
+
+  while (Dynarr_length (db->runes) < min_pos &&
+         (data->pixpos + data->blank_width <= data->max_pixpos))
+    add_blank_rune (data, NULL, 0);
+
+  return Dynarr_length (db->runes);
+}
+
+/* #### Urk!  Should also handle begin-glyphs and end-glyphs in
+   modeline extents. */
+static Charcount
+add_glyph_to_fstring_db_runes (pos_data *data, Lisp_Object glyph,
+                               Charcount pos, Charcount min_pos, Charcount max_pos)
+{
+  /* This function has been Mule-ized. */
+  Charcount end;
+  struct display_block *db = data->db;
+  struct glyph_block gb;
+
+  data->blank_width = space_width (XWINDOW (data->window));
+  while (Dynarr_length (db->runes) < pos)
+    add_blank_rune (data, NULL, 0);
+
+  end = Dynarr_length (db->runes) + 1;
+  if (max_pos != -1)
+    end = min (max_pos, end);
+
+  gb.glyph = glyph;
+  gb.extent = Qnil;
+  add_glyph_rune (data, &gb, BEGIN_GLYPHS, 0, 0);
+  pos++;
+
+  while (Dynarr_length (db->runes) < pos &&
+         (data->pixpos + data->blank_width <= data->max_pixpos))
+    add_blank_rune (data, NULL, 0);
+
+  return Dynarr_length (db->runes);
+}
+
+/* If max_pos is == -1, it is considered to be infinite.  The same is
+   true of max_pixsize. */
+#define SET_CURRENT_MODE_CHARS_PIXSIZE                                  \
+  if (Dynarr_length (data->db->runes))                                  \
+    cur_pixsize = data->pixpos - Dynarr_atp (data->db->runes, 0)->xpos; \
+  else                                                                  \
+    cur_pixsize = 0;
+
+/* Note that this function does "positions" in terms of characters and
+   not in terms of columns.  This is necessary to make the formatting
+   work correctly when proportional width fonts are used in the
+   modeline. */
+static Charcount
+generate_fstring_runes (struct window *w, pos_data *data, Charcount pos,
+                        Charcount min_pos, Charcount max_pos,
+                        Lisp_Object elt, int depth, int max_pixsize,
+                        face_index findex, int type)
+{
+  /* This function has been Mule-ized. */
+  /* #### The other losing things in this function are:
+
+     -- C zero-terminated-string lossage.
+     -- Non-printable characters should be converted into something
+        appropriate (e.g. ^F) instead of blindly being printed anyway.
+   */
+
+tail_recurse:
+  if (depth > 10)
+    goto invalid;
+
+  depth++;
+
+  if (STRINGP (elt))
+    {
+      /* A string.  Add to the display line and check for %-constructs
+         within it. */
+
+      Bufbyte *this = XSTRING_DATA (elt);
+
+      while ((pos < max_pos || max_pos == -1) && *this)
+        {
+          Bufbyte *last = this;
+
+          while (*this && *this != '%')
+            this++;
+
+          if (this != last)
+            {
+              /* The string is just a string. */
+              Charcount size =
+                bytecount_to_charcount (last, this - last) + pos;
+              Charcount tmp_max = (max_pos == -1 ? size : min (size, max_pos));
+
+              pos = add_string_to_fstring_db_runes (data, last, pos, pos,
+                                                    tmp_max);
+            }
+          else /* *this == '%' */
+            {
+              Charcount spec_width = 0;
+
+              this++; /* skip over '%' */
+
+              /* We can't allow -ve args due to the "%-" construct.
+               * Argument specifies minwidth but not maxwidth
+               * (maxwidth can be specified by
+               * (<negative-number> . <stuff>) modeline elements)
+               */
+              while (isdigit (*this))
+                {
+                  spec_width = spec_width * 10 + (*this - '0');
+                  this++;
+                }
+              spec_width += pos;
+
+              if (*this == 'M')
+                {
+                  pos = generate_fstring_runes (w, data, pos, spec_width,
+                                                max_pos, Vglobal_mode_string,
+                                                depth, max_pixsize, findex,
+                                                type);
+                }
+              else if (*this == '-')
+                {
+                  Charcount num_to_add;
+
+                  if (max_pixsize < 0)
+                    num_to_add = 0;
+                  else if (max_pos != -1)
+                    num_to_add = max_pos - pos;
+                  else
+                    {
+                      int cur_pixsize;
+                      int dash_pixsize;
+                      Bufbyte ch = '-';
+                      SET_CURRENT_MODE_CHARS_PIXSIZE;
+
+                      dash_pixsize =
+                        redisplay_text_width_string (w, findex, &ch, Qnil, 0,
+                                                     1);
+
+                      num_to_add = (max_pixsize - cur_pixsize) / dash_pixsize;
+                      num_to_add++;
+                    }
+
+                  while (num_to_add--)
+                    pos = add_string_to_fstring_db_runes
+                      (data, (CONST Bufbyte *) "-", pos, pos, max_pos);
+                }
+              else if (*this != 0)
+                {
+                  Bufbyte *str;
+                  Emchar ch = charptr_emchar (this);
+                  decode_mode_spec (w, ch, type);
+
+                  str = Dynarr_atp (mode_spec_bufbyte_string, 0);
+                  pos = add_string_to_fstring_db_runes (data,str, pos, pos,
+                                                        max_pos);
+                }
+
+              /* NOT this++.  There could be any sort of character at
+                 the current position. */
+              INC_CHARPTR (this);
+            }
+
+          if (max_pixsize > 0)
+            {
+              int cur_pixsize;
+              SET_CURRENT_MODE_CHARS_PIXSIZE;
+
+              if (cur_pixsize >= max_pixsize)
+                break;
+            }
+        }
+    }
+  else if (SYMBOLP (elt))
+    {
+      /* A symbol: process the value of the symbol recursively
+         as if it appeared here directly. */
+      Lisp_Object tem = symbol_value_in_buffer (elt, w->buffer);
+
+      if (!UNBOUNDP (tem))
+        {
+          /* If value is a string, output that string literally:
+             don't check for % within it.  */
+          if (STRINGP (tem))
+            {
+              pos =
+                add_string_to_fstring_db_runes
+                (data, XSTRING_DATA (tem), pos, min_pos, max_pos);
+            }
+          /* Give up right away for nil or t.  */
+          else if (!EQ (tem, elt))
+            {
+              elt = tem;
+              goto tail_recurse;
+            }
+        }
+    }
+  else if (GENERIC_SPECIFIERP (elt))
+    {
+      Lisp_Object window, tem;
+      XSETWINDOW (window, w);
+      tem = specifier_instance_no_quit (elt, Qunbound, window,
+					ERROR_ME_NOT, 0, Qzero);
+      if (!UNBOUNDP (tem))
+	{
+	  elt = tem;
+	  goto tail_recurse;
+	}
+    }
+  else if (CONSP (elt))
+    {
+      /* A cons cell: four distinct cases.
+       * If first element is a string or a cons, process all the elements
+       * and effectively concatenate them.
+       * If first element is a negative number, truncate displaying cdr to
+       * at most that many characters.  If positive, pad (with spaces)
+       * to at least that many characters.
+       * If first element is a symbol, process the cadr or caddr recursively
+       * according to whether the symbol's value is non-nil or nil.
+       * If first element is a face, process the cdr recursively
+       * without altering the depth.
+       */
+      Lisp_Object car, tem;
+
+      car = XCAR (elt);
+      if (SYMBOLP (car))
+        {
+          elt = XCDR (elt);
+          if (!CONSP (elt))
+            goto invalid;
+          tem = symbol_value_in_buffer (car, w->buffer);
+          /* elt is now the cdr, and we know it is a cons cell.
+             Use its car if CAR has a non-nil value.  */
+          if (!UNBOUNDP (tem))
+            {
+              if (!NILP (tem))
+                {
+                  elt = XCAR (elt);
+                  goto tail_recurse;
+                }
+            }
+          /* Symbol's value is nil (or symbol is unbound)
+           * Get the cddr of the original list
+           * and if possible find the caddr and use that.
+           */
+          elt = XCDR (elt);
+          if (NILP (elt))
+            ;
+          else if (!CONSP (elt))
+            goto invalid;
+          else
+            {
+              elt = XCAR (elt);
+              goto tail_recurse;
+            }
+        }
+      else if (INTP (car))
+        {
+          Charcount lim = XINT (car);
+
+          elt = XCDR (elt);
+
+          if (lim < 0)
+            {
+              /* Negative int means reduce maximum width.
+               * DO NOT change MIN_PIXPOS here!
+               * (20 -10 . foo) should truncate foo to 10 col
+               * and then pad to 20.
+               */
+              if (max_pos == -1)
+                max_pos = pos - lim;
+              else
+                max_pos = min (max_pos, pos - lim);
+            }
+          else if (lim > 0)
+            {
+              /* Padding specified.  Don't let it be more than
+               * current maximum.
+               */
+              lim += pos;
+              if (max_pos != -1 && lim > max_pos)
+                lim = max_pos;
+              /* If that's more padding than already wanted, queue it.
+               * But don't reduce padding already specified even if
+               * that is beyond the current truncation point.
+               */
+              if (lim > min_pos)
+                min_pos = lim;
+            }
+          goto tail_recurse;
+        }
+      else if (STRINGP (car) || CONSP (car))
+        {
+          int limit = 50;
+          /* LIMIT is to protect against circular lists.  */
+          while (CONSP (elt) && --limit > 0
+                 && (pos < max_pos || max_pos == -1))
+            {
+              pos = generate_fstring_runes (w, data, pos, pos, max_pos,
+                                            XCAR (elt), depth,
+                                            max_pixsize, findex, type);
+              elt = XCDR (elt);
+            }
+        }
+      else if (EXTENTP (car))
+        {
+          struct extent *ext = XEXTENT (car);
+
+          if (EXTENT_LIVE_P (ext))
+            {
+              face_index old_findex = data->findex;
+              Lisp_Object face;
+              Lisp_Object font_inst;
+              face_index new_findex;
+              Bytecount start = data->bytepos;
+
+              face = extent_face (ext);
+              if (FACEP (face))
+                {
+                  /* #### needs to merge faces, sigh */
+                  /* #### needs to handle list of faces */
+                  new_findex = get_builtin_face_cache_index (w, face);
+                  /* !!#### not right; needs to compute the max height of
+                     all the charsets */
+                  font_inst = WINDOW_FACE_CACHEL_FONT (w, new_findex,
+                                                       Vcharset_ascii);
+
+                  data->dl->ascent = max (data->dl->ascent,
+                                          XFONT_INSTANCE (font_inst)->ascent);
+                  data->dl->descent = max (data->dl->descent,
+                                           XFONT_INSTANCE (font_inst)->
+                                           descent);
+                }
+              else
+                new_findex = old_findex;
+
+              data->findex = new_findex;
+              pos = generate_fstring_runes (w, data, pos, pos, max_pos,
+                                            XCDR (elt), depth - 1,
+                                            max_pixsize, new_findex, type);
+              data->findex = old_findex;
+              Dynarr_add (formatted_string_extent_dynarr, ext);
+              Dynarr_add (formatted_string_extent_start_dynarr, start);
+              Dynarr_add (formatted_string_extent_end_dynarr, data->bytepos);
+            }
+        }
+    }
+  else if (GLYPHP (elt))
+    {
+      pos = add_glyph_to_fstring_db_runes (data, elt, pos, pos, max_pos);
+    }
+  else
+    {
+    invalid:
+      pos =
+        add_string_to_fstring_db_runes
+          (data, (CONST Bufbyte *) GETTEXT ("*invalid*"), pos, min_pos,
+           max_pos);
+    }
+
+  if (min_pos > pos)
+    {
+      add_string_to_fstring_db_runes (data, (CONST Bufbyte *) "", pos, min_pos,
+                                      -1);
+    }
+
+  return pos;
+}
+
+/* The caller is responsible for freeing the returned string. */
+Bufbyte *
+generate_formatted_string (struct window *w, Lisp_Object format_str,
+			   Lisp_Object result_str, face_index findex, int type)
+{
+  struct display_line *dl;
+  struct display_block *db;
+  int elt = 0;
+
+  dl = &formatted_string_display_line;
+  db = get_display_block_from_line (dl, TEXT);
+  Dynarr_reset (db->runes);
+
+  generate_formatted_string_db (format_str, result_str, w, dl, db, findex, 0,
+                                -1, type);
+
+  Dynarr_reset (formatted_string_emchar_dynarr);
+  while (elt < Dynarr_length (db->runes))
+    {
+      if (Dynarr_atp (db->runes, elt)->type == RUNE_CHAR)
+	Dynarr_add (formatted_string_emchar_dynarr,
+		    Dynarr_atp (db->runes, elt)->object.chr.ch);
+      elt++;
+    }
+
+  return
+    convert_emchar_string_into_malloced_string
+    ( Dynarr_atp (formatted_string_emchar_dynarr, 0),
+      Dynarr_length (formatted_string_emchar_dynarr), 0);
+}
+
+/* Update just the modeline.  Assumes the desired display structs.  If
+   they do not have a modeline block, it does nothing. */
+static void
+regenerate_modeline (struct window *w)
+{
+  display_line_dynarr *dla = window_display_lines (w, DESIRED_DISP);
+
+  if (!Dynarr_length (dla) || !Dynarr_atp (dla, 0)->modeline)
+    return;
+  else
+    {
+      generate_modeline (w, Dynarr_atp (dla, 0), DESIRED_DISP);
+      redisplay_update_line (w, 0, 0, 0);
+    }
+}
+
+/* Make sure that modeline display line is present in the given
+   display structs if the window has a modeline and update that
+   line.  Returns true if a modeline was needed. */
+static int
+ensure_modeline_generated (struct window *w, int type)
+{
+  int need_modeline;
+
+  /* minibuffer windows don't have modelines */
+  if (MINI_WINDOW_P (w))
+    need_modeline = 0;
+  /* windows which haven't had it turned off do */
+  else if (WINDOW_HAS_MODELINE_P (w))
+    need_modeline = 1;
+  /* windows which have it turned off don't have a divider if there is
+     a horizontal scrollbar */
+  else if (window_scrollbar_height (w))
+    need_modeline = 0;
+  /* and in this case there is none */
+  else
+    need_modeline = 1;
+
+  if (need_modeline)
+    {
+      display_line_dynarr *dla;
+
+      dla = window_display_lines (w, type);
+
+      /* We don't care if there is a display line which is not
+         currently a modeline because it is definitely going to become
+         one if we have gotten to this point. */
+      if (Dynarr_length (dla) == 0)
+	{
+	  if (Dynarr_largest (dla) > 0)
+	    {
+	      struct display_line *mlp = Dynarr_atp (dla, 0);
+	      Dynarr_add (dla, *mlp);
+	    }
+	  else
+	    {
+	      struct display_line modeline;
+	      xzero (modeline);
+	      Dynarr_add (dla, modeline);
+	    }
+	}
+
+      /* If we're adding a new place marker go ahead and generate the
+         modeline so that it is available for use by
+         window_modeline_height. */
+      generate_modeline (w, Dynarr_atp (dla, 0), type);
+    }
+
+  return need_modeline;
+}
+
+/* #### Kludge or not a kludge.  I tend towards the former. */
+int
+real_current_modeline_height (struct window *w)
+{
+  Fset_marker (w->start[CMOTION_DISP],  w->start[CURRENT_DISP],  w->buffer);
+  Fset_marker (w->pointm[CMOTION_DISP], w->pointm[CURRENT_DISP], w->buffer);
+
+  if (ensure_modeline_generated (w, CMOTION_DISP))
+    {
+      display_line_dynarr *dla = window_display_lines (w, CMOTION_DISP);
+
+      if (Dynarr_length (dla))
+	{
+	  if (Dynarr_atp (dla, 0)->modeline)
+	    return (Dynarr_atp (dla, 0)->ascent +
+		    Dynarr_atp (dla, 0)->descent);
+	}
+    }
+  return 0;
+}
+
+
+/***************************************************************************/
+/*								*/
+/*                            displayable string routines			*/
+/*								*/
+/***************************************************************************/
+
+/* Given a position for a string in a window, ensure that the given
+   display line DL accurately represents the text on a line starting
+   at the given position.
+
+   Yes, this is duplicating the code of create_text_block, but it
+   looked just too hard to change create_text_block to handle strings
+   *and* buffers. We already make a distinction between the two
+   elsewhere in the code so I think unifying them would require a
+   complete MULE rewrite. Besides, the other distinction is that these
+   functions cover text that the user *cannot edit* so we can remove
+   everything to do with cursors, minibuffers etc. Eventually the
+   modeline routines should be modified to use this code as it copes
+   with many more types of display situation. */
+
+static Bufpos
+create_string_text_block (struct window *w, Lisp_Object disp_string,
+			  struct display_line *dl,
+			  Bufpos start_pos,
+			  prop_block_dynarr **prop,
+			  face_index default_face)
+{
+  struct frame *f = XFRAME (w->frame);
+  /* Note that a lot of the buffer controlled stuff has been left in
+     because you might well want to make use of it (selective display
+     etc), its just the buffer text that we do not use. However, it
+     seems to be possible for buffer to be nil sometimes so protect
+     against this case. */
+  struct buffer *b = BUFFERP (w->buffer) ? XBUFFER (w->buffer) : 0;
+  struct device *d = XDEVICE (f->device);
+  struct Lisp_String* s = XSTRING (disp_string);
+
+  /* we're working with these a lot so precalculate them */
+  Bytecount slen = XSTRING_LENGTH (disp_string);
+  Bytecount bi_string_zv = slen;
+  Bytind bi_start_pos = charcount_to_bytecount (string_data (s), start_pos);
+
+  pos_data data;
+
+  int truncate_win = b ? window_truncation_on (w) : 0;
+  int end_glyph_width = 0;
+
+  /* we're going to ditch selective display for static text, its an
+     FSF thing and invisble extents are the way to go
+     here. Implementing it also relies on a number of buffer-specific
+     functions that we don't have the luxury of being able to use
+     here. */
+
+  /* The variable ctl-arrow allows the user to specify what characters
+     can actually be displayed and which octal should be used for.
+     #### This variable should probably have some rethought done to
+     it.
+
+     #### It would also be really nice if you could specify that
+     the characters come out in hex instead of in octal.  Mule
+     does that by adding a ctl-hexa variable similar to ctl-arrow,
+     but that's bogus -- we need a more general solution.  I
+     think you need to extend the concept of display tables
+     into a more general conversion mechanism.  Ideally you
+     could specify a Lisp function that converts characters,
+     but this violates the Second Golden Rule and besides would
+     make things way way way way slow.
+
+     So instead, we extend the display-table concept, which was
+     historically limited to 256-byte vectors, to one of the
+     following:
+
+     a) A 256-entry vector, for backward compatibility;
+     b) char-table, mapping characters to values;
+     c) range-table, mapping ranges of characters to values;
+     d) a list of the above.
+
+     The (d) option allows you to specify multiple display tables
+     instead of just one.  Each display table can specify conversions
+     for some characters and leave others unchanged.  The way the
+     character gets displayed is determined by the first display table
+     with a binding for that character.  This way, you could call a
+     function `enable-hex-display' that adds a hex display-table to
+     the list of display tables for the current buffer.
+
+     #### ...not yet implemented...  Also, we extend the concept of
+     "mapping" to include a printf-like spec.  Thus you can make all
+     extended characters show up as hex with a display table like
+     this:
+
+         #s(range-table data ((256 524288) (format "%x")))
+
+     Since more than one display table is possible, you have
+     great flexibility in mapping ranges of characters.  */
+  Emchar printable_min = b ? (CHAR_OR_CHAR_INTP (b->ctl_arrow)
+			  ? XCHAR_OR_CHAR_INT (b->ctl_arrow)
+			  : ((EQ (b->ctl_arrow, Qt) || EQ (b->ctl_arrow, Qnil))
+			     ? 255 : 160)) : 255;
+
+  Lisp_Object face_dt, window_dt;
+
+  /* The text display block for this display line. */
+  struct display_block *db = get_display_block_from_line (dl, TEXT);
+
+  /* The first time through the main loop we need to force the glyph
+     data to be updated. */
+  int initial = 1;
+
+  /* Apparently the new extent_fragment_update returns an end position
+     equal to the position passed in if there are no more runs to be
+     displayed. */
+  int no_more_frags = 0;
+
+  dl->used_prop_data = 0;
+  dl->num_chars = 0;
+
+  /* set up faces to use for clearing areas, used by
+     output_display_line */
+  dl->default_findex = default_face;
+  if (default_face)
+    {
+      dl->left_margin_findex = default_face;
+      dl->right_margin_findex = default_face;
+    }
+  else
+    {
+      dl->left_margin_findex = 
+	get_builtin_face_cache_index (w, Vleft_margin_face);
+      dl->right_margin_findex = 
+	get_builtin_face_cache_index (w, Vright_margin_face);
+    }
+
+  xzero (data);
+  data.ef = extent_fragment_new (disp_string, f);
+
+  /* These values are used by all of the rune addition routines.  We add
+     them to this structure for ease of passing. */
+  data.d = d;
+  XSETWINDOW (data.window, w);
+  data.db = db;
+  data.dl = dl;
+
+  data.bi_bufpos = bi_start_pos;
+  data.pixpos = dl->bounds.left_in;
+  data.last_charset = Qunbound;
+  data.last_findex = default_face;
+  data.result_str = Qnil;
+  data.string = disp_string;
+
+  /* Set the right boundary adjusting it to take into account any end
+     glyph.  Save the width of the end glyph for later use. */
+  data.max_pixpos = dl->bounds.right_in;
+#if 0
+  if (truncate_win)
+    end_glyph_width = GLYPH_CACHEL_WIDTH (w, TRUN_GLYPH_INDEX);
+  else
+    end_glyph_width = GLYPH_CACHEL_WIDTH (w, CONT_GLYPH_INDEX);
+#endif
+  data.max_pixpos -= end_glyph_width;
+
+  data.cursor_type = NO_CURSOR;
+  data.cursor_x = -1;
+
+  data.start_col = 0;
+  /* I don't think we want this, string areas should not scroll with
+     the window 
+  data.start_col = w->hscroll;
+  data.bi_start_col_enabled = (w->hscroll ? bi_start_pos : 0);
+  */
+  data.bi_start_col_enabled = 0;
+  data.hscroll_glyph_width_adjust = 0;
+
+  /* We regenerate the line from the very beginning. */
+  Dynarr_reset (db->runes);
+
+  /* Why is this less than or equal and not just less than?  If the
+     starting position is already equal to the maximum we can't add
+     anything else, right?  Wrong.  We might still have a newline to
+     add.  A newline can use the room allocated for an end glyph since
+     if we add it we know we aren't going to be adding any end
+     glyph. */
+
+  /* #### Chuck -- I think this condition should be while (1).
+     Otherwise if (e.g.) there is one begin-glyph and one end-glyph
+     and the begin-glyph ends exactly at the end of the window, the
+     end-glyph and text might not be displayed.  while (1) ensures
+     that the loop terminates only when either (a) there is
+     propagation data or (b) the end-of-line or end-of-buffer is hit.
+
+     #### Also I think you need to ensure that the operation
+     "add begin glyphs; add end glyphs; add text" is atomic and
+     can't get interrupted in the middle.  If you run off the end
+     of the line during that operation, then you keep accumulating
+     propagation data until you're done.  Otherwise, if the (e.g.)
+     there's a begin glyph at a particular position and attempting
+     to display that glyph results in window-end being hit and
+     propagation data being generated, then the character at that
+     position won't be displayed.
+
+     #### See also the comment after the end of this loop, below.
+     */
+  while (data.pixpos <= data.max_pixpos)
+    {
+      /* #### This check probably should not be necessary. */
+      if (data.bi_bufpos > bi_string_zv)
+	{
+	  /* #### urk!  More of this lossage! */
+	  data.bi_bufpos--;
+	  goto done;
+	}
+
+      /* Check for face changes. */
+      if (initial || (!no_more_frags && data.bi_bufpos == data.ef->end))
+	{
+	  /* Now compute the face and begin/end-glyph information. */
+	  data.findex =
+	    /* Remember that the extent-fragment routines deal in Bytind's. */
+	    extent_fragment_update (w, data.ef, data.bi_bufpos);
+	  /* This is somewhat cheesy but the alternative is to
+             propagate default_face into extent_fragment_update. */
+	  if (data.findex == DEFAULT_INDEX)
+	    data.findex = default_face;
+
+	  get_display_tables (w, data.findex, &face_dt, &window_dt);
+
+	  if (data.bi_bufpos == data.ef->end)
+	    no_more_frags = 1;
+	}
+      initial = 0;
+
+      /* Determine what is next to be displayed.  We first handle any
+         glyphs returned by glyphs_at_bufpos.  If there are no glyphs to
+         display then we determine what to do based on the character at the
+         current buffer position. */
+
+      /* If the current position is covered by an invisible extent, do
+         nothing (except maybe add some ellipses).
+
+	 #### The behavior of begin and end-glyphs at the edge of an
+	 invisible extent should be investigated further.  This is
+	 fairly low priority though. */
+      if (data.ef->invisible)
+	{
+	  /* #### Chuck, perhaps you could look at this code?  I don't
+	     really know what I'm doing. */
+	  if (*prop)
+	    {
+	      Dynarr_free (*prop);
+	      *prop = 0;
+	    }
+
+	  /* The extent fragment code only sets this when we should
+	     really display the ellipses.  It makes sure the ellipses
+	     don't get displayed more than once in a row. */
+	  if (data.ef->invisible_ellipses)
+	    {
+	      struct glyph_block gb;
+
+	      data.ef->invisible_ellipses_already_displayed = 1;
+	      data.ef->invisible_ellipses = 0;
+	      gb.extent = Qnil;
+	      gb.glyph = Vinvisible_text_glyph;
+	      *prop = add_glyph_rune (&data, &gb, BEGIN_GLYPHS, 0,
+				      GLYPH_CACHEL (w, INVIS_GLYPH_INDEX));
+	      /* Perhaps they shouldn't propagate if the very next thing
+		 is to display a newline (for compatibility with
+		 selective-display-ellipses)?  Maybe that's too
+		 abstruse. */
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* #### What if we we're dealing with a display table? */
+	  if (data.start_col)
+	    data.start_col--;
+
+	  if (data.bi_bufpos == bi_string_zv)
+	    goto done;
+	  else
+	    INC_CHARBYTIND (string_data (s), data.bi_bufpos);
+	}
+
+      /* If there is propagation data, then it represents the current
+         buffer position being displayed.  Add them and advance the
+         position counter.  This might also add the minibuffer
+         prompt. */
+      else if (*prop)
+	{
+	  dl->used_prop_data = 1;
+	  *prop = add_propagation_runes (prop, &data);
+
+	  if (*prop)
+	    goto done;	/* gee, a really narrow window */
+	  else if (data.bi_bufpos == bi_string_zv)
+	    goto done;
+	  else if (data.bi_bufpos < 0)
+	    /* #### urk urk urk! Aborts are not very fun! Fix this please! */
+	    data.bi_bufpos = 0;
+	  else
+	    INC_CHARBYTIND (string_data (s), data.bi_bufpos);
+	}
+
+      /* If there are end glyphs, add them to the line.  These are
+	 the end glyphs for the previous run of text.  We add them
+	 here rather than doing them at the end of handling the
+	 previous run so that glyphs at the beginning and end of
+	 a line are handled correctly. */
+      else if (Dynarr_length (data.ef->end_glyphs) > 0)
+	{
+	  *prop = add_glyph_runes (&data, END_GLYPHS);
+	  if (*prop)
+	    goto done;
+	}
+
+      /* If there are begin glyphs, add them to the line. */
+      else if (Dynarr_length (data.ef->begin_glyphs) > 0)
+	{
+	  *prop = add_glyph_runes (&data, BEGIN_GLYPHS);
+	  if (*prop)
+	    goto done;
+	}
+
+      /* If at end-of-buffer, we've already processed begin and
+	 end-glyphs at this point and there's no text to process,
+	 so we're done. */
+      else if (data.bi_bufpos == bi_string_zv)
+	goto done;
+
+      else
+	{
+	  Lisp_Object entry = Qnil;
+	  /* Get the character at the current buffer position. */
+	  data.ch = string_char (s, data.bi_bufpos);
+	  if (!NILP (face_dt) || !NILP (window_dt))
+	    entry = display_table_entry (data.ch, face_dt, window_dt);
+
+	  /* If there is a display table entry for it, hand it off to
+             add_disp_table_entry_runes and let it worry about it. */
+	  if (!NILP (entry) && !EQ (entry, make_char (data.ch)))
+	    {
+	      *prop = add_disp_table_entry_runes (&data, entry);
+
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* Check if we have hit a newline character.  If so, add a marker
+             to the line and end this loop. */
+	  else if (data.ch == '\n')
+	    {
+	      /* We aren't going to be adding an end glyph so give its
+                 space back in order to make sure that the cursor can
+                 fit. */
+	      data.max_pixpos += end_glyph_width;
+	      goto done;
+	    }
+
+	  /* If the current character is considered to be printable, then
+             just add it. */
+	  else if (data.ch >= printable_min)
+	    {
+	      *prop = add_emchar_rune (&data);
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* If the current character is a tab, determine the next tab
+             starting position and add a blank rune which extends from the
+             current pixel position to that starting position. */
+	  else if (data.ch == '\t')
+	    {
+	      int tab_start_pixpos = data.pixpos;
+	      int next_tab_start;
+	      int char_tab_width;
+	      int prop_width = 0;
+
+	      if (data.start_col > 1)
+		tab_start_pixpos -= (space_width (w) * (data.start_col - 1));
+
+	      next_tab_start =
+		next_tab_position (w, tab_start_pixpos,
+				   dl->bounds.left_in +
+				   data.hscroll_glyph_width_adjust);
+	      if (next_tab_start > data.max_pixpos)
+		{
+		  prop_width = next_tab_start - data.max_pixpos;
+		  next_tab_start = data.max_pixpos;
+		}
+	      data.blank_width = next_tab_start - data.pixpos;
+	      char_tab_width =
+		(next_tab_start - tab_start_pixpos) / space_width (w);
+
+	      *prop = add_blank_rune (&data, w, char_tab_width);
+
+	      /* add_blank_rune is only supposed to be called with
+                 sizes guaranteed to fit in the available space. */
+	      assert (!(*prop));
+
+	      if (prop_width)
+		{
+		  struct prop_block pb;
+		  *prop = Dynarr_new (prop_block);
+
+		  pb.type = PROP_BLANK;
+		  pb.data.p_blank.width = prop_width;
+		  pb.data.p_blank.findex = data.findex;
+		  Dynarr_add (*prop, pb);
+
+		  goto done;
+		}
+	    }
+
+	  /* If character is a control character, pass it off to
+             add_control_char_runes.
+
+	     The is_*() routines have undefined results on
+	     arguments outside of the range [-1, 255].  (This
+	     often bites people who carelessly use `char' instead
+	     of `unsigned char'.)
+	     */
+	  else if (data.ch < 0x100 && iscntrl ((Bufbyte) data.ch))
+	    {
+	      *prop = add_control_char_runes (&data, b);
+
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* If the character is above the ASCII range and we have not
+             already handled it, then print it as an octal number. */
+	  else if (data.ch >= 0200)
+	    {
+	      *prop = add_octal_runes (&data);
+
+	      if (*prop)
+		goto done;
+	    }
+
+	  /* Assume the current character is considered to be printable,
+             then just add it. */
+	  else
+	    {
+	      *prop = add_emchar_rune (&data);
+	      if (*prop)
+		goto done;
+	    }
+
+	  INC_CHARBYTIND (string_data (s), data.bi_bufpos);
+	}
+    }
+
+done:
+
+  /* Determine the starting point of the next line if we did not hit the
+     end of the buffer. */
+  if (data.bi_bufpos < bi_string_zv)
+    {
+      /* #### This check is not correct.  If the line terminated
+	 due to a begin-glyph or end-glyph hitting window-end, then
+	 data.ch will not point to the character at data.bi_bufpos.  If
+	 you make the two changes mentioned at the top of this loop,
+	 you should be able to say '(if (*prop))'.  That should also
+	 make it possible to eliminate the data.bi_bufpos < BI_BUF_ZV (b)
+	 check. */
+
+      /* The common case is that the line ended because we hit a newline.
+         In that case, the next character is just the next buffer
+         position. */
+      if (data.ch == '\n')
+	{
+	  INC_CHARBYTIND (string_data (s), data.bi_bufpos);
+	}
+
+      /* Otherwise we have a buffer line which cannot fit on one display
+         line. */
+      else
+	{
+	  struct glyph_block gb;
+	  struct glyph_cachel *cachel;
+
+	  /* If the line is to be truncated then we actually have to look
+             for the next newline.  We also add the end-of-line glyph which
+             we know will fit because we adjusted the right border before
+             we starting laying out the line. */
+	  data.max_pixpos += end_glyph_width;
+	  data.findex = default_face;
+	  gb.extent = Qnil;
+
+	  if (truncate_win)
+	    {
+	      Bytind bi_pos;
+
+	      /* Now find the start of the next line. */
+	      bi_pos = bi_find_next_emchar_in_string (s, '\n', data.bi_bufpos, 1);
+
+	      data.cursor_type = NO_CURSOR;
+	      data.bi_bufpos = bi_pos;
+	      gb.glyph = Vtruncation_glyph;
+	      cachel = GLYPH_CACHEL (w, TRUN_GLYPH_INDEX);
+	    }
+	  else
+	    {
+	      /* The cursor can never be on the continuation glyph. */
+	      data.cursor_type = NO_CURSOR;
+
+	      /* data.bi_bufpos is already at the start of the next line. */
+
+	      gb.glyph = Vcontinuation_glyph;
+	      cachel = GLYPH_CACHEL (w, CONT_GLYPH_INDEX);
+	    }
+
+	  if (end_glyph_width)
+	    add_glyph_rune (&data, &gb, BEGIN_GLYPHS, 0, cachel);
+
+	  if (truncate_win && data.bi_bufpos == bi_string_zv)
+	    {
+	      CONST Bufbyte* endb = charptr_n_addr (string_data (s), bi_string_zv);
+	      DEC_CHARPTR (endb);
+	      if (charptr_emchar (endb) != '\n')
+		{
+		  /* #### Damn this losing shit. */
+		  data.bi_bufpos++;
+		}
+	    }
+	}
+    }
+  else if (data.bi_bufpos == bi_string_zv)
+    {
+      /* create_text_block () adds a bogus \n marker here which screws
+	 up subwindow display. Since we never have a cursor in the
+	 gutter we can safely ignore it. */
+    }
+  /* Calculate left whitespace boundary. */
+  {
+    int elt = 0;
+
+    /* Whitespace past a newline is considered right whitespace. */
+    while (elt < Dynarr_length (db->runes))
+      {
+	struct rune *rb = Dynarr_atp (db->runes, elt);
+
+	if ((rb->type == RUNE_CHAR && rb->object.chr.ch == ' ')
+	    || rb->type == RUNE_BLANK)
+	  {
+	    dl->bounds.left_white += rb->width;
+	    elt++;
+	  }
+	else
+	  elt = Dynarr_length (db->runes);
+      }
+  }
+
+  /* Calculate right whitespace boundary. */
+  {
+    int elt = Dynarr_length (db->runes) - 1;
+    int done = 0;
+
+    while (!done && elt >= 0)
+      {
+	struct rune *rb = Dynarr_atp (db->runes, elt);
+
+	if (!(rb->type == RUNE_CHAR && rb->object.chr.ch < 0x100
+	    && isspace (rb->object.chr.ch))
+	    && !rb->type == RUNE_BLANK)
+	  {
+	    dl->bounds.right_white = rb->xpos + rb->width;
+	    done = 1;
+	  }
+
+	elt--;
+
+      }
+
+    /* The line is blank so everything is considered to be right
+       whitespace. */
+    if (!done)
+      dl->bounds.right_white = dl->bounds.left_in;
+  }
+
+  /* Set the display blocks bounds. */
+  db->start_pos = dl->bounds.left_in;
+  if (Dynarr_length (db->runes))
+    {
+      struct rune *rb = Dynarr_atp (db->runes, Dynarr_length (db->runes) - 1);
+
+      db->end_pos = rb->xpos + rb->width;
+    }
+  else
+    db->end_pos = dl->bounds.right_white;
+
+  /* update line height parameters */
+  if (!data.new_ascent && !data.new_descent)
+    {
+      /* We've got a blank line so initialize these values from the default
+         face. */
+      default_face_font_info (data.window, &data.new_ascent,
+			      &data.new_descent, 0, 0, 0);
+    }
+
+  if (data.max_pixmap_height)
+    {
+      int height = data.new_ascent + data.new_descent;
+      int pix_ascent, pix_descent;
+
+      pix_descent = data.max_pixmap_height * data.new_descent / height;
+      pix_ascent = data.max_pixmap_height - pix_descent;
+
+      data.new_ascent = max (data.new_ascent, pix_ascent);
+      data.new_descent = max (data.new_descent, pix_descent);
+    }
+
+  dl->ascent = data.new_ascent;
+  dl->descent = data.new_descent;
+
+  {
+    unsigned short ascent = (unsigned short) XINT (w->minimum_line_ascent);
+
+    if (dl->ascent < ascent)
+      dl->ascent = ascent;
+  }
+  {
+    unsigned short descent = (unsigned short) XINT (w->minimum_line_descent);
+
+    if (dl->descent < descent)
+      dl->descent = descent;
+  }
+
+  dl->cursor_elt = data.cursor_x;
+  /* #### lossage lossage lossage! Fix this shit! */
+  if (data.bi_bufpos > bi_string_zv)
+    dl->end_bufpos = buffer_or_string_bytind_to_bufpos (disp_string, bi_string_zv);
+  else
+    dl->end_bufpos = buffer_or_string_bytind_to_bufpos (disp_string, data.bi_bufpos) - 1;
+  if (truncate_win)
+    data.dl->num_chars = 
+      string_column_at_point (s, dl->end_bufpos, b ? XINT (b->tab_width) : 8);
+  else
+    /* This doesn't correctly take into account tabs and control
+       characters but if the window isn't being truncated then this
+       value isn't going to end up being used anyhow. */
+    data.dl->num_chars = dl->end_bufpos - dl->bufpos;
+
+  /* #### handle horizontally scrolled line with text none of which
+     was actually laid out. */
+
+  /* #### handle any remainder of overlay arrow */
+
+  if (*prop == ADD_FAILED)
+    *prop = NULL;
+
+  if (truncate_win && *prop)
+    {
+      Dynarr_free (*prop);
+      *prop = NULL;
+    }
+
+  extent_fragment_delete (data.ef);
+
+  /* #### If we started at EOB, then make sure we return a value past
+     it so that regenerate_window will exit properly.  This is bogus.
+     The main loop should get fixed so that it isn't necessary to call
+     this function if we are already at EOB. */
+
+  if (data.bi_bufpos == bi_string_zv && bi_start_pos == bi_string_zv)
+    return bytecount_to_charcount (string_data (s), data.bi_bufpos) + 1; /* Yuck! */
+  else
+    return bytecount_to_charcount (string_data (s), data.bi_bufpos);
+}
+
+/* Given a display line and a starting position, ensure that the
+   contents of the display line accurately represent the visual
+   representation of the buffer contents starting from the given
+   position when displayed in the given window.  The display line ends
+   when the contents of the line reach the right boundary of the given
+   window. 
+   
+   This is very similar to generate_display_line but with the same
+   limitations as create_string_text_block. I have taken the liberty
+   of fixing the bytind stuff though.*/
+
+static Bufpos
+generate_string_display_line (struct window *w, Lisp_Object disp_string,
+			      struct display_line *dl,
+			      Bufpos start_pos,
+			      prop_block_dynarr **prop,
+			      face_index default_face)
+{
+  Bufpos ret_bufpos;
+
+  /* you must set bounds before calling this. */
+  
+  /* Reset what this line is using. */
+  if (dl->display_blocks)
+    Dynarr_reset (dl->display_blocks);
+  if (dl->left_glyphs)
+    {
+      Dynarr_free (dl->left_glyphs);
+      dl->left_glyphs = 0;
+    }
+  if (dl->right_glyphs)
+    {
+      Dynarr_free (dl->right_glyphs);
+      dl->right_glyphs = 0;
+    }
+
+  /* We aren't generating a modeline at the moment. */
+  dl->modeline = 0;
+
+  /* Create a display block for the text region of the line. */
+  ret_bufpos = create_string_text_block (w, disp_string, dl, start_pos,
+					 prop, default_face);
+  dl->bufpos = start_pos;
+  if (dl->end_bufpos < dl->bufpos)
+    dl->end_bufpos = dl->bufpos;
+
+  /* If there are left glyphs associated with any character in the
+     text block, then create a display block to handle them. */
+  if (dl->left_glyphs != NULL && Dynarr_length (dl->left_glyphs))
+    create_left_glyph_block (w, dl, 0);
+
+  /* If there are right glyphs associated with any character in the
+     text block, then create a display block to handle them. */
+  if (dl->right_glyphs != NULL && Dynarr_length (dl->right_glyphs))
+    create_right_glyph_block (w, dl);
+
+  return ret_bufpos;
+}
+
+/* This is ripped off from regenerate_window. All we want to do is
+   loop through elements in the string creating display lines until we
+   have covered the provided area. Simple really.  */
+void
+generate_displayable_area (struct window *w, Lisp_Object disp_string,
+			   int xpos, int ypos, int width, int height,
+			   display_line_dynarr* dla,
+			   Bufpos start_pos,
+			   face_index default_face)
+{
+  int yend = ypos + height;
+  Charcount s_zv;
+
+  prop_block_dynarr *prop = 0;
+  layout_bounds bounds;
+  assert (dla);
+
+  Dynarr_reset (dla);
+  /* if there's nothing to do then do nothing. code after this assumes
+     there is something to do. */
+  if (NILP (disp_string))
+    return;
+
+  s_zv = XSTRING_CHAR_LENGTH (disp_string);
+
+  bounds.left_out = xpos;
+  bounds.right_out = xpos + width;
+  /* The inner boundaries mark where the glyph margins are located. */
+  bounds.left_in = bounds.left_out + window_left_margin_width (w);
+  bounds.right_in = bounds.right_out - window_right_margin_width (w);
+  /* We cannot fully calculate the whitespace boundaries as they
+     depend on the contents of the line being displayed. */
+  bounds.left_white = bounds.left_in;
+  bounds.right_white = bounds.right_in;
+
+  while (ypos < yend)
+    {
+      struct display_line dl;
+      struct display_line *dlp;
+      Bufpos next_pos;
+      int local;
+
+      if (Dynarr_length (dla) < Dynarr_largest (dla))
+	{
+	  dlp = Dynarr_atp (dla, Dynarr_length (dla));
+	  local = 0;
+	}
+      else
+	{
+
+	  xzero (dl);
+	  dlp = &dl;
+	  local = 1;
+	}
+
+      dlp->bounds = bounds;
+      dlp->offset = 0;
+      next_pos = generate_string_display_line (w, disp_string, dlp, start_pos,
+					       &prop, default_face);
+      /* we need to make sure that we continue along the line if there
+         is more left to display otherwise we just end up redisplaying
+         the same chunk over and over again. */
+      if (next_pos == start_pos && next_pos < s_zv)
+	start_pos++;
+      else
+	start_pos = next_pos;
+
+      dlp->ypos = ypos + dlp->ascent;
+      ypos = dlp->ypos + dlp->descent;
+
+      if (ypos > yend)
+	{
+	  int visible_height = dlp->ascent + dlp->descent;
+
+	  dlp->clip = (ypos - yend);
+	  visible_height -= dlp->clip;
+
+	  if (visible_height < VERTICAL_CLIP (w, 1))
+	    {
+	      if (local)
+		free_display_line (dlp);
+	      break;
+	    }
+	}
+      else
+	dlp->clip = 0;
+
+      Dynarr_add (dla, *dlp);
+
+      /* #### This type of check needs to be done down in the
+	 generate_display_line call. */
+      if (start_pos >= s_zv)
+	break;
+    }
+
+  if (prop)
+    Dynarr_free (prop);
+}
+
+
+/***************************************************************************/
+/*									   */
+/*                        window-regeneration routines                     */
+/*									   */
+/***************************************************************************/
+
+/* For a given window and starting position in the buffer it contains,
+   ensure that the TYPE display lines accurately represent the
+   presentation of the window.  We pass the buffer instead of getting
+   it from the window since redisplay_window may have temporarily
+   changed it to the echo area buffer. */
+
+static void
+regenerate_window (struct window *w, Bufpos start_pos, Bufpos point, int type)
+{
+  struct frame *f = XFRAME (w->frame);
+  struct buffer *b = XBUFFER (w->buffer);
+  int ypos = WINDOW_TEXT_TOP (w);
+  int yend;	/* set farther down */
+  int yclip = WINDOW_TEXT_TOP_CLIP (w);
+
+  prop_block_dynarr *prop;
+  layout_bounds bounds;
+  display_line_dynarr *dla;
+  int need_modeline;
+
+  /* The lines had better exist by this point. */
+  if (!(dla = window_display_lines (w, type)))
+    abort ();
+  Dynarr_reset (dla);
+  w->max_line_len = 0;
+
+  /* Normally these get updated in redisplay_window but it is possible
+     for this function to get called from some other points where that
+     update may not have occurred.  This acts as a safety check. */
+  if (!Dynarr_length (w->face_cachels))
+    reset_face_cachels (w);
+  if (!Dynarr_length (w->glyph_cachels))
+    reset_glyph_cachels (w);
+
+  Fset_marker (w->start[type], make_int (start_pos), w->buffer);
+  Fset_marker (w->pointm[type], make_int (point), w->buffer);
+  w->last_point_x[type] = -1;
+  w->last_point_y[type] = -1;
+
+  /* Make sure a modeline is in the structs if needed. */
+  need_modeline = ensure_modeline_generated (w, type);
+
+  /* Wait until here to set this so that the structs have a modeline
+     generated in the case where one didn't exist. */
+  yend = WINDOW_TEXT_BOTTOM (w);
+
+  bounds = calculate_display_line_boundaries (w, 0);
+
+  /* 97/3/14 jhod: stuff added here to support pre-prompts (used for input systems) */
+  if (MINI_WINDOW_P (w)
+      && (!NILP (Vminibuf_prompt) || !NILP (Vminibuf_preprompt))
+      && !echo_area_active (f)
+      && start_pos == BUF_BEGV (b))
+    {
+      struct prop_block pb;
+      Lisp_Object string;
+      prop = Dynarr_new (prop_block);
+
+      string = concat2(Vminibuf_preprompt, Vminibuf_prompt);
+      pb.type = PROP_MINIBUF_PROMPT;
+      pb.data.p_string.str = XSTRING_DATA(string);
+      pb.data.p_string.len = XSTRING_LENGTH(string);
+      Dynarr_add (prop, pb);
+    }
+  else
+    prop = 0;
+
+  while (ypos < yend)
+    {
+      struct display_line dl;
+      struct display_line *dlp;
+      int local;
+
+      if (Dynarr_length (dla) < Dynarr_largest (dla))
+	{
+	  dlp = Dynarr_atp (dla, Dynarr_length (dla));
+	  local = 0;
+	}
+      else
+	{
+
+	  xzero (dl);
+	  dlp = &dl;
+	  local = 1;
+	}
+
+      dlp->bounds = bounds;
+      dlp->offset = 0;
+      start_pos = generate_display_line (w, dlp, 1, start_pos, &prop, type);
+
+      if (yclip > dlp->ascent)
+	{
+	  /* this should never happen, but if it does just display the
+	     whole line */
+	  yclip = 0;
+	}
+
+      dlp->ypos = (ypos + dlp->ascent) - yclip;
+      ypos = dlp->ypos + dlp->descent;
+
+      /* See if we've been asked to start midway through a line, for
+         partial display line scrolling. */
+      if (yclip)		
+	{
+	  dlp->top_clip = yclip;
+	  yclip = 0;
+	}
+      else
+	dlp->top_clip = 0;
+
+      if (ypos > yend)
+	{
+	  int visible_height = dlp->ascent + dlp->descent;
+
+	  dlp->clip = (ypos - yend);
+	  /* Although this seems strange we could have a single very
+	     tall line visible for which we need to account for both
+	     the top clip and the bottom clip. */
+	  visible_height -= (dlp->clip + dlp->top_clip);
+
+	  if (visible_height < VERTICAL_CLIP (w, 1))
+	    {
+	      if (local)
+		free_display_line (dlp);
+	      break;
+	    }
+	}
+      else
+	dlp->clip = 0;
+
+      if (dlp->cursor_elt != -1)
+	{
+	  /* #### This check is steaming crap.  Have to get things
+             fixed so when create_text_block hits EOB, we're done,
+             period. */
+	  if (w->last_point_x[type] == -1)
+	    {
+	      w->last_point_x[type] = dlp->cursor_elt;
+	      w->last_point_y[type] = Dynarr_length (dla);
+	    }
+	  else
+	    {
+	      /* #### This means that we've added a cursor at EOB
+                 twice.  Yuck oh yuck. */
+	      struct display_block *db =
+		get_display_block_from_line (dlp, TEXT);
+
+	      Dynarr_atp (db->runes, dlp->cursor_elt)->cursor_type = NO_CURSOR;
+	      dlp->cursor_elt = -1;
+	    }
+	}
+
+      if (dlp->num_chars > w->max_line_len)
+	w->max_line_len = dlp->num_chars;
+
+      Dynarr_add (dla, *dlp);
+
+      /* #### This isn't right, but it is close enough for now. */
+      w->window_end_pos[type] = start_pos;
+
+      /* #### This type of check needs to be done down in the
+	 generate_display_line call. */
+      if (start_pos > BUF_ZV (b))
+	break;
+    }
+
+  if (prop)
+    Dynarr_free (prop);
+
+  /* #### More not quite right, but close enough. */
+  /* #### Ben sez: apparently window_end_pos[] is measured
+     as the number of characters between the window end and the
+     end of the buffer?  This seems rather weirdo.  What's
+     the justification for this? */
+  w->window_end_pos[type] = BUF_Z (b) - w->window_end_pos[type];
+
+  if (need_modeline)
+    {
+      /* We know that this is the right thing to use because we put it
+         there when we first started working in this function. */
+      generate_modeline (w, Dynarr_atp (dla, 0), type);
+    }
+}
+
+#define REGEN_INC_FIND_START_END		\
+  do {						\
+    /* Determine start and end of lines. */	\
+    if (!Dynarr_length (cdla))			\
+      return 0;					\
+    else					\
+      {						\
+	if (Dynarr_atp (cdla, 0)->modeline && Dynarr_atp (ddla, 0)->modeline) \
+	  {					\
+	    dla_start = 1;			\
+	  }					\
+	else if (!Dynarr_atp (cdla, 0)->modeline \
+		 && !Dynarr_atp (ddla, 0)->modeline) \
+	  {					\
+	    dla_start = 0;			\
+	  }					\
+	else					\
+	  abort ();	/* structs differ */	\
+						\
+	dla_end = Dynarr_length (cdla) - 1;	\
+      }						\
+						\
+    start_pos = (Dynarr_atp (cdla, dla_start)->bufpos \
+		 + Dynarr_atp (cdla, dla_start)->offset); \
+    /* If this isn't true, then startp has changed and we need to do a \
+       full regen. */				\
+    if (startp != start_pos)			\
+      return 0;					\
+						\
+    /* Point is outside the visible region so give up. */ \
+    if (pointm < start_pos)			\
+      return 0;					\
+						\
+  } while (0)
+
+/* This attempts to incrementally update the display structures.  It
+   returns a boolean indicating success or failure.  This function is
+   very similar to regenerate_window_incrementally and is in fact only
+   called from that function.  However, because of the nature of the
+   changes it deals with it sometimes makes different assumptions
+   which can lead to success which are much more difficult to make
+   when dealing with buffer changes. */
+
+static int
+regenerate_window_extents_only_changed (struct window *w, Bufpos startp,
+					Bufpos pointm,
+					Charcount beg_unchanged,
+					Charcount end_unchanged)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  display_line_dynarr *cdla = window_display_lines (w, CURRENT_DISP);
+  display_line_dynarr *ddla = window_display_lines (w, DESIRED_DISP);
+
+  int dla_start = 0;
+  int dla_end, line;
+  int first_line, last_line;
+  Bufpos start_pos;
+  /* Don't define this in the loop where it is used because we
+     definitely want its value to survive between passes. */
+  prop_block_dynarr *prop = NULL;
+
+  /* If we don't have any buffer change recorded but the modiff flag has
+     been incremented, then fail.  I'm not sure of the exact circumstances
+     under which this can happen, but I believe that it is probably a
+     reasonable happening. */
+  if (!point_visible (w, pointm, CURRENT_DISP)
+      || XINT (w->last_modified[CURRENT_DISP]) < BUF_MODIFF (b))
+    return 0;
+
+  /* If the cursor is moved we attempt to update it.  If we succeed we
+     go ahead and proceed with the optimization attempt. */
+  if (!EQ (Fmarker_buffer (w->last_point[CURRENT_DISP]), w->buffer)
+      || pointm != marker_position (w->last_point[CURRENT_DISP]))
+    {
+      struct frame *f = XFRAME (w->frame);
+      struct device *d = XDEVICE (f->device);
+      struct frame *sel_f = device_selected_frame (d);
+      int success = 0;
+
+      if (w->last_point_x[CURRENT_DISP] != -1
+	  && w->last_point_y[CURRENT_DISP] != -1)
+	{
+
+	  if (redisplay_move_cursor (w, pointm, WINDOW_TTY_P (w)))
+	    {
+	      /* Always regenerate the modeline in case it is
+                 displaying the current line or column. */
+	      regenerate_modeline (w);
+	      success = 1;
+	    }
+	}
+      else if (w != XWINDOW (FRAME_SELECTED_WINDOW (sel_f)))
+	{
+	  if (f->modeline_changed)
+	    regenerate_modeline (w);
+	  success = 1;
+	}
+
+      if (!success)
+	return 0;
+    }
+
+  if (beg_unchanged == -1 && end_unchanged == -1)
+    return 1;
+
+  /* assert: There are no buffer modifications or they are all below the
+     visible region.  We assume that regenerate_window_incrementally has
+     not called us unless this is true.  */
+
+  REGEN_INC_FIND_START_END;
+
+  /* If the changed are starts before the visible area, give up. */
+  if (beg_unchanged < startp)
+    return 0;
+
+  /* Find what display line the extent changes first affect. */
+  line = dla_start;
+  while (line <= dla_end)
+    {
+      struct display_line *dl = Dynarr_atp (cdla, line);
+      Bufpos lstart = dl->bufpos + dl->offset;
+      Bufpos lend = dl->end_bufpos + dl->offset;
+
+      if (beg_unchanged >= lstart && beg_unchanged <= lend)
+	break;
+
+      line++;
+    }
+
+  /* If the changes are below the visible area then if point hasn't
+     moved return success otherwise fail in order to be safe. */
+  if (line > dla_end)
+    {
+      if (EQ (Fmarker_buffer (w->last_point[CURRENT_DISP]), w->buffer)
+	  && pointm == marker_position (w->last_point[CURRENT_DISP]))
+	return 1;
+      else
+	return 0;
+    }
+
+  /* At this point we know what line the changes first affect.  We now
+     begin redrawing lines as long as we are still in the affected
+     region and the line's size and positioning don't change.
+     Otherwise we fail.  If we fail we will have altered the desired
+     structs which could lead to an assertion failure.  However, if we
+     fail the next thing that is going to happen is a full regen so we
+     will actually end up being safe. */
+  w->last_modified[DESIRED_DISP] = make_int (BUF_MODIFF (b));
+  w->last_facechange[DESIRED_DISP] = make_int (BUF_FACECHANGE (b));
+  Fset_marker (w->last_start[DESIRED_DISP], make_int (startp), w->buffer);
+  Fset_marker (w->last_point[DESIRED_DISP], make_int (pointm), w->buffer);
+
+  first_line = last_line = line;
+  while (line <= dla_end)
+    {
+      Bufpos old_start, old_end, new_start;
+      struct display_line *cdl = Dynarr_atp (cdla, line);
+      struct display_line *ddl = Dynarr_atp (ddla, line);
+      struct display_block *db;
+      int initial_size;
+
+      assert (cdl->bufpos == ddl->bufpos);
+      assert (cdl->end_bufpos == ddl->end_bufpos);
+      assert (cdl->offset == ddl->offset);
+
+      db = get_display_block_from_line (ddl, TEXT);
+      initial_size = Dynarr_length (db->runes);
+      old_start = ddl->bufpos + ddl->offset;
+      old_end = ddl->end_bufpos + ddl->offset;
+
+      /* If this is the first line being updated and it used
+         propagation data, fail.  Otherwise we'll be okay because
+         we'll have the necessary propagation data. */
+      if (line == first_line && ddl->used_prop_data)
+	return 0;
+
+      new_start = generate_display_line (w, ddl, 0, ddl->bufpos + ddl->offset,
+					 &prop, DESIRED_DISP);
+      ddl->offset = 0;
+
+      /* #### If there is propagated stuff the fail.  We could
+         probably actually deal with this if the line had propagated
+         information when originally created by a full
+         regeneration. */
+      if (prop)
+	{
+	  Dynarr_free (prop);
+	  return 0;
+	}
+
+      /* If any line position parameters have changed or a
+         cursor has disappeared or disappeared, fail.  */
+      db = get_display_block_from_line (ddl, TEXT);
+      if (cdl->ypos != ddl->ypos
+	  || cdl->ascent != ddl->ascent
+	  || cdl->descent != ddl->descent
+	  || cdl->top_clip != ddl->top_clip
+	  || (cdl->cursor_elt != -1 && ddl->cursor_elt == -1)
+	  || (cdl->cursor_elt == -1 && ddl->cursor_elt != -1)
+	  || old_start != ddl->bufpos
+	  || old_end != ddl->end_bufpos
+	  || initial_size != Dynarr_length (db->runes))
+	{
+	  return 0;
+	}
+
+      if (ddl->cursor_elt != -1)
+	{
+	  w->last_point_x[DESIRED_DISP] = ddl->cursor_elt;
+	  w->last_point_y[DESIRED_DISP] = line;
+	}
+
+      last_line = line;
+
+      /* If the extent changes end on the line we just updated then
+         we're done.  Otherwise go on to the next line. */
+      if (end_unchanged <= ddl->end_bufpos)
+	break;
+      else
+	line++;
+    }
+
+  redisplay_update_line (w, first_line, last_line, 1);
+  return 1;
+}
+
+/* Attempt to update the display data structures based on knowledge of
+   the changed region in the buffer.  Returns a boolean indicating
+   success or failure.  If this function returns a failure then a
+   regenerate_window _must_ be performed next in order to maintain
+   invariants located here. */
+
+static int
+regenerate_window_incrementally (struct window *w, Bufpos startp,
+				 Bufpos pointm)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  display_line_dynarr *cdla = window_display_lines (w, CURRENT_DISP);
+  display_line_dynarr *ddla = window_display_lines (w, DESIRED_DISP);
+  Charcount beg_unchanged, end_unchanged;
+  Charcount extent_beg_unchanged, extent_end_unchanged;
+
+  int dla_start = 0;
+  int dla_end, line;
+  Bufpos start_pos;
+
+  /* If this function is called, the current and desired structures
+     had better be identical.  If they are not, then that is a bug. */
+  assert (Dynarr_length (cdla) == Dynarr_length (ddla));
+
+  /* We don't handle minibuffer windows yet.  The minibuffer prompt
+     screws us up. */
+  if (MINI_WINDOW_P (w))
+    return 0;
+
+  extent_beg_unchanged = BUF_EXTENT_BEGIN_UNCHANGED (b);
+  extent_end_unchanged = (BUF_EXTENT_END_UNCHANGED (b) == -1
+			  ? -1
+			  : BUF_Z (b) - BUF_EXTENT_END_UNCHANGED (b));
+
+  /* If nothing has changed in the buffer, then make sure point is ok
+     and succeed. */
+  if (BUF_BEGIN_UNCHANGED (b) == -1 && BUF_END_UNCHANGED (b) == -1)
+    return regenerate_window_extents_only_changed (w, startp, pointm,
+						   extent_beg_unchanged,
+						   extent_end_unchanged);
+
+  /* We can't deal with deleted newlines. */
+  if (BUF_NEWLINE_WAS_DELETED (b))
+    return 0;
+
+  beg_unchanged = BUF_BEGIN_UNCHANGED (b);
+  end_unchanged = (BUF_END_UNCHANGED (b) == -1
+		   ? -1
+		   : BUF_Z (b) - BUF_END_UNCHANGED (b));
+
+  REGEN_INC_FIND_START_END;
+
+  /* If the changed area starts before the visible area, give up. */
+  if (beg_unchanged < startp)
+    return 0;
+
+  /* Find what display line the buffer changes first affect. */
+  line = dla_start;
+  while (line <= dla_end)
+    {
+      struct display_line *dl = Dynarr_atp (cdla, line);
+      Bufpos lstart = dl->bufpos + dl->offset;
+      Bufpos lend = dl->end_bufpos + dl->offset;
+
+      if (beg_unchanged >= lstart && beg_unchanged <= lend)
+	break;
+
+      line++;
+    }
+
+  /* If the changes are below the visible area then if point hasn't
+     moved return success otherwise fail in order to be safe. */
+  if (line > dla_end)
+    return regenerate_window_extents_only_changed (w, startp, pointm,
+						   extent_beg_unchanged,
+						   extent_end_unchanged);
+  else
+    /* At this point we know what line the changes first affect.  We
+       now redraw that line.  If the changes are contained within it
+       we are going to succeed and can update just that one line.
+       Otherwise we fail.  If we fail we will have altered the desired
+       structs which could lead to an assertion failure.  However, if
+       we fail the next thing that is going to happen is a full regen
+       so we will actually end up being safe. */
+    {
+      Bufpos new_start;
+      prop_block_dynarr *prop = NULL;
+      struct display_line *cdl = Dynarr_atp (cdla, line);
+      struct display_line *ddl = Dynarr_atp (ddla, line);
+
+      assert (cdl->bufpos == ddl->bufpos);
+      assert (cdl->end_bufpos == ddl->end_bufpos);
+      assert (cdl->offset == ddl->offset);
+
+      /* If the last rune is already a continuation glyph, fail.
+         #### We should be able to handle this better. */
+      {
+	struct display_block *db = get_display_block_from_line (ddl, TEXT);
+	if (Dynarr_length (db->runes))
+	  {
+	    struct rune *rb =
+	      Dynarr_atp (db->runes, Dynarr_length (db->runes) - 1);
+
+	    if (rb->type == RUNE_DGLYPH
+		&& EQ (rb->object.dglyph.glyph, Vcontinuation_glyph))
+	      return 0;
+	  }
+      }
+
+      /* If the line was generated using propagation data, fail. */
+      if (ddl->used_prop_data)
+	return 0;
+
+      new_start = generate_display_line (w, ddl, 0, ddl->bufpos + ddl->offset,
+					 &prop, DESIRED_DISP);
+      ddl->offset = 0;
+
+      /* If there is propagated stuff then it is pretty much a
+         guarantee that more than just the one line is affected. */
+      if (prop)
+	{
+	  Dynarr_free (prop);
+	  return 0;
+	}
+
+      /* If the last rune is now a continuation glyph, fail. */
+      {
+	struct display_block *db = get_display_block_from_line (ddl, TEXT);
+	if (Dynarr_length (db->runes))
+	  {
+	    struct rune *rb =
+	      Dynarr_atp (db->runes, Dynarr_length (db->runes) - 1);
+
+	    if (rb->type == RUNE_DGLYPH
+		&& EQ (rb->object.dglyph.glyph, Vcontinuation_glyph))
+	      return 0;
+	  }
+      }
+
+      /* If any line position parameters have changed or a
+         cursor has disappeared or disappeared, fail. */
+      if (cdl->ypos != ddl->ypos
+	  || cdl->ascent != ddl->ascent
+	  || cdl->descent != ddl->descent
+	  || cdl->top_clip != ddl->top_clip
+	  || (cdl->cursor_elt != -1 && ddl->cursor_elt == -1)
+	  || (cdl->cursor_elt == -1 && ddl->cursor_elt != -1))
+	{
+	  return 0;
+	}
+
+      /* If the changed area also ends on this line, then we may be in
+         business.  Update everything and return success. */
+      if (end_unchanged >= ddl->bufpos && end_unchanged <= ddl->end_bufpos)
+	{
+	  w->last_modified[DESIRED_DISP] = make_int (BUF_MODIFF (b));
+	  w->last_facechange[DESIRED_DISP] = make_int (BUF_FACECHANGE (b));
+	  Fset_marker (w->last_start[DESIRED_DISP], make_int (startp),
+		       w->buffer);
+	  Fset_marker (w->last_point[DESIRED_DISP], make_int (pointm),
+		       w->buffer);
+
+	  if (ddl->cursor_elt != -1)
+	    {
+	      w->last_point_x[DESIRED_DISP] = ddl->cursor_elt;
+	      w->last_point_y[DESIRED_DISP] = line;
+	    }
+
+	  redisplay_update_line (w, line, line, 1);
+	  regenerate_modeline (w);
+
+	  /* #### For now we just flush the cache until this has been
+             tested.  After that is done, this should correct the
+             cache directly. */
+	  Dynarr_reset (w->line_start_cache);
+
+	  /* Adjust the extent changed boundaries to remove any
+             overlap with the buffer changes since we've just
+             successfully updated that area. */
+	  if (extent_beg_unchanged != -1
+	      && extent_beg_unchanged >= beg_unchanged
+	      && extent_beg_unchanged < end_unchanged)
+	    extent_beg_unchanged = end_unchanged;
+
+	  if (extent_end_unchanged != -1
+	      && extent_end_unchanged >= beg_unchanged
+	      && extent_end_unchanged < end_unchanged)
+	    extent_end_unchanged = beg_unchanged - 1;
+
+	  if (extent_end_unchanged <= extent_beg_unchanged)
+	    extent_beg_unchanged = extent_end_unchanged = -1;
+
+	  /* This could lead to odd results if it fails, but since the
+             buffer changes update succeeded this probably will to.
+             We already know that the extent changes start at or after
+             the line because we checked before entering the loop. */
+	  if (extent_beg_unchanged != -1
+	      && extent_end_unchanged != -1
+	      && ((extent_beg_unchanged < ddl->bufpos)
+		  || (extent_end_unchanged > ddl->end_bufpos)))
+	    return regenerate_window_extents_only_changed (w, startp, pointm,
+							   extent_beg_unchanged,
+							   extent_end_unchanged);
+	  else
+	    return 1;
+	}
+    }
+
+  /* Oh, well. */
+  return 0;
+}
+
+/* Given a window and a point, update the given display lines such
+   that point is displayed in the middle of the window.
+   Return the window's new start position. */
+
+static Bufpos
+regenerate_window_point_center (struct window *w, Bufpos point, int type)
+{
+  Bufpos startp;
+
+  /* We need to make sure that the modeline is generated so that the
+     window height can be calculated correctly. */
+  ensure_modeline_generated (w, type);
+
+  startp = start_with_line_at_pixpos (w, point, window_half_pixpos (w));
+  regenerate_window (w, startp, point, type);
+  Fset_marker (w->start[type], make_int (startp), w->buffer);
+
+  return startp;
+}
+
+/* Given a window and a set of display lines, return a boolean
+   indicating whether the given point is contained within. */
+
+static int
+point_visible (struct window *w, Bufpos point, int type)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  display_line_dynarr *dla = window_display_lines (w, type);
+  int first_line;
+
+  if (Dynarr_length (dla) && Dynarr_atp (dla, 0)->modeline)
+    first_line = 1;
+  else
+    first_line = 0;
+
+  if (Dynarr_length (dla) > first_line)
+    {
+      Bufpos start, end;
+      struct display_line *dl = Dynarr_atp (dla, first_line);
+
+      start = dl->bufpos;
+      end = BUF_Z (b) - w->window_end_pos[type] - 1;
+
+      if (point >= start && point <= end)
+	{
+	  if (!MINI_WINDOW_P (w) && scroll_on_clipped_lines)
+	    {
+	      dl = Dynarr_atp (dla, Dynarr_length (dla) - 1);
+
+	      if (point >= (dl->bufpos + dl->offset)
+		  && point <= (dl->end_bufpos + dl->offset))
+		return !dl->clip;
+	      else
+		return 1;
+	    }
+	  else
+	    return 1;
+	}
+      else
+	return 0;
+    }
+  else
+    return 0;
+}
+
+/* Return pixel position the middle of the window, not including the
+   modeline and any potential horizontal scrollbar. */
+
+int
+window_half_pixpos (struct window *w)
+{
+  return WINDOW_TEXT_TOP (w) + (WINDOW_TEXT_HEIGHT (w) >> 1);
+}
+
+/* Return the display line which is currently in the middle of the
+   window W for display lines TYPE. */
+
+int
+line_at_center (struct window *w, int type, Bufpos start, Bufpos point)
+{
+  display_line_dynarr *dla;
+  int half;
+  int elt;
+  int first_elt = (MINI_WINDOW_P (w) ? 0 : 1);
+
+  if (type == CMOTION_DISP)
+    regenerate_window (w, start, point, type);
+
+  dla = window_display_lines (w, type);
+  half = window_half_pixpos (w);
+
+  for (elt = first_elt; elt < Dynarr_length (dla); elt++)
+    {
+      struct display_line *dl = Dynarr_atp (dla, elt);
+      int line_bot = dl->ypos + dl->descent;
+
+      if (line_bot > half)
+	return elt;
+    }
+
+  /* We may not have a line at the middle if the end of the buffer is
+     being displayed. */
+  return -1;
+}
+
+/* Return a value for point that would place it at the beginning of
+   the line which is in the middle of the window. */
+
+Bufpos
+point_at_center (struct window *w, int type, Bufpos start, Bufpos point)
+{
+  /* line_at_center will regenerate the display structures, if necessary. */
+  int line = line_at_center (w, type, start, point);
+
+  if (line == -1)
+    return BUF_ZV (XBUFFER (w->buffer));
+  else
+    {
+      display_line_dynarr *dla = window_display_lines (w, type);
+      struct display_line *dl = Dynarr_atp (dla, line);
+
+      return dl->bufpos;
+    }
+}
+
+/* For a given window, ensure that the current visual representation
+   is accurate. */
+
+static void
+redisplay_window (Lisp_Object window, int skip_selected)
+{
+  struct window *w = XWINDOW (window);
+  struct frame *f = XFRAME (w->frame);
+  struct device *d = XDEVICE (f->device);
+  Lisp_Object old_buffer = w->buffer;
+  Lisp_Object the_buffer = w->buffer;
+  struct buffer *b;
+  int echo_active = 0;
+  int startp = 1;
+  int pointm;
+  int old_startp = 1;
+  int old_pointm = 1;
+  int selected_in_its_frame;
+  int selected_globally;
+  int skip_output = 0;
+  int truncation_changed;
+  int inactive_minibuffer =
+    (MINI_WINDOW_P (w) &&
+     (f != device_selected_frame (d)) &&
+     !is_surrogate_for_selected_frame (f));
+
+  /* #### In the new world this function actually does a bunch of
+     optimizations such as buffer-based scrolling, but none of that is
+     implemented yet. */
+
+  /* If this is a combination window, do its children; that's all.
+     The selected window is always a leaf so we don't check for
+     skip_selected here. */
+  if (!NILP (w->vchild))
+    {
+      redisplay_windows (w->vchild, skip_selected);
+      return;
+    }
+  if (!NILP (w->hchild))
+    {
+      redisplay_windows (w->hchild, skip_selected);
+      return;
+    }
+
+  /* Is this window the selected window on its frame? */
+  selected_in_its_frame = (w == XWINDOW (FRAME_SELECTED_WINDOW (f)));
+  selected_globally =
+      selected_in_its_frame &&
+      EQ(DEVICE_CONSOLE(d), Vselected_console) &&
+      XDEVICE(CONSOLE_SELECTED_DEVICE(XCONSOLE(DEVICE_CONSOLE(d)))) == d &&
+      XFRAME(DEVICE_SELECTED_FRAME(d)) == f;
+  if (skip_selected && selected_in_its_frame)
+    return;
+
+  /* It is possible that the window is not fully initialized yet. */
+  if (NILP (w->buffer))
+    return;
+
+  if (MINI_WINDOW_P (w) && echo_area_active (f))
+    {
+      w->buffer = the_buffer = Vecho_area_buffer;
+      echo_active = 1;
+    }
+
+  b = XBUFFER (w->buffer);
+
+  if (echo_active)
+    {
+      old_pointm = selected_globally
+                   ? BUF_PT (b)
+                   : marker_position (w->pointm[CURRENT_DISP]);
+      pointm = 1;
+    }
+  else
+    {
+      if (selected_globally)
+	{
+	  pointm = BUF_PT (b);
+	}
+      else
+	{
+	  pointm = marker_position (w->pointm[CURRENT_DISP]);
+
+	  if (pointm < BUF_BEGV (b))
+	    pointm = BUF_BEGV (b);
+	  else if (pointm > BUF_ZV (b))
+	    pointm = BUF_ZV (b);
+	}
+    }
+  Fset_marker (w->pointm[DESIRED_DISP], make_int (pointm), the_buffer);
+
+  /* If the buffer has changed we have to invalidate all of our face
+     cache elements. */
+  if ((!echo_active && b != window_display_buffer (w))
+      || !Dynarr_length (w->face_cachels)
+      || f->faces_changed)
+    reset_face_cachels (w);
+  else
+    mark_face_cachels_as_not_updated (w);
+
+  /* Ditto the glyph cache elements, although we do *not* invalidate
+     the cache purely because glyphs have changed - this is now
+     handled by the dirty flag.*/
+  if ((!echo_active && b != window_display_buffer (w))
+      || !Dynarr_length (w->glyph_cachels))
+    reset_glyph_cachels (w);
+  else
+    mark_glyph_cachels_as_not_updated (w);
+
+  /* If the marker's buffer is not the window's buffer, then we need
+     to find a new starting position. */
+  if (!MINI_WINDOW_P (w)
+      && !EQ (Fmarker_buffer (w->start[CURRENT_DISP]), w->buffer))
+    {
+      startp = regenerate_window_point_center (w, pointm, DESIRED_DISP);
+
+      goto regeneration_done;
+    }
+
+  if (echo_active)
+    {
+      old_startp = marker_position (w->start[CURRENT_DISP]);
+      startp = 1;
+    }
+  else
+    {
+      startp = marker_position (w->start[CURRENT_DISP]);
+      if (startp < BUF_BEGV (b))
+	startp = BUF_BEGV (b);
+      else if (startp > BUF_ZV (b))
+	startp = BUF_ZV (b);
+    }
+  Fset_marker (w->start[DESIRED_DISP], make_int (startp), the_buffer);
+
+  truncation_changed = (find_window_mirror (w)->truncate_win !=
+			window_truncation_on (w));
+
+  /* If w->force_start is set, then some function set w->start and we
+     should display from there and change point, if necessary, to
+     ensure that it is visible. */
+  if (w->force_start || inactive_minibuffer)
+    {
+      w->force_start = 0;
+      w->last_modified[DESIRED_DISP] = Qzero;
+      w->last_facechange[DESIRED_DISP] = Qzero;
+
+      regenerate_window (w, startp, pointm, DESIRED_DISP);
+
+      if (!point_visible (w, pointm, DESIRED_DISP) && !inactive_minibuffer)
+	{
+	  pointm = point_at_center (w, DESIRED_DISP, 0, 0);
+
+	  if (selected_globally)
+	    BUF_SET_PT (b, pointm);
+
+	  Fset_marker (w->pointm[DESIRED_DISP], make_int (pointm),
+		       the_buffer);
+
+	  /* #### BUFU amounts of overkill just to get the cursor
+             location marked properly.  FIX ME FIX ME FIX ME */
+	  regenerate_window (w, startp, pointm, DESIRED_DISP);
+	}
+
+      goto regeneration_done;
+    }
+
+  /* If nothing has changed since the last redisplay, then we just
+     need to make sure that point is still visible. */
+  if (XINT (w->last_modified[CURRENT_DISP]) >= BUF_MODIFF (b)
+      && XINT (w->last_facechange[CURRENT_DISP]) >= BUF_FACECHANGE (b)
+      && pointm >= startp
+      /* This check is to make sure we restore the minibuffer after a
+         temporary change to the echo area. */
+      && !(MINI_WINDOW_P (w) && f->buffers_changed)
+      && !f->frame_changed
+      && !truncation_changed
+      /* check whether start is really at the begining of a line  GE */
+      && (!w->start_at_line_beg || beginning_of_line_p (b, startp))
+      )
+    {
+      /* Check if the cursor has actually moved. */
+      if (EQ (Fmarker_buffer (w->last_point[CURRENT_DISP]), w->buffer)
+	  && pointm == marker_position (w->last_point[CURRENT_DISP])
+	  && selected_globally
+	  && !w->windows_changed
+	  && !f->clip_changed
+	  && !f->extents_changed
+	  && !f->faces_changed
+	  && !f->glyphs_changed
+	  && !f->subwindows_changed
+	  && !f->subwindows_state_changed
+	  && !f->point_changed
+	  && !f->windows_structure_changed)
+	{
+	  /* If not, we're done. */
+	  if (f->modeline_changed)
+	    regenerate_modeline (w);
+
+	  skip_output = 1;
+	  goto regeneration_done;
+	}
+      else
+	{
+	  /* If the new point is visible in the redisplay structures,
+             then let the output update routines handle it, otherwise
+             do things the hard way. */
+	  if (!w->windows_changed
+	      && !f->clip_changed
+	      && !f->extents_changed
+	      && !f->faces_changed
+	      && !f->glyphs_changed
+	      && !f->subwindows_changed
+	      && !f->subwindows_state_changed
+	      && !f->windows_structure_changed)
+	    {
+	      if (point_visible (w, pointm, CURRENT_DISP)
+		  && w->last_point_x[CURRENT_DISP] != -1
+		  && w->last_point_y[CURRENT_DISP] != -1)
+		{
+		  if (redisplay_move_cursor (w, pointm, FRAME_TTY_P (f)))
+		    {
+		      /* Always regenerate in case it is displaying
+                         the current line or column. */
+		      regenerate_modeline (w);
+
+		      skip_output = 1;
+		      goto regeneration_done;
+		    }
+		}
+	      else if (!selected_in_its_frame && !f->point_changed)
+		{
+		  if (f->modeline_changed)
+		    regenerate_modeline (w);
+
+		  skip_output = 1;
+		  goto regeneration_done;
+		}
+	    }
+
+	  /* If we weren't able to take the shortcut method, then use
+             the brute force method. */
+	  regenerate_window (w, startp, pointm, DESIRED_DISP);
+
+	  if (point_visible (w, pointm, DESIRED_DISP))
+	    goto regeneration_done;
+	}
+    }
+
+  /* Check if the starting point is no longer at the beginning of a
+     line, in which case find a new starting point.  We also recenter
+     if our start position is equal to point-max.  Otherwise we'll end
+     up with a blank window. */
+  else if (((w->start_at_line_beg || MINI_WINDOW_P (w))
+	    && !(startp == BUF_BEGV (b)
+		 || BUF_FETCH_CHAR (b, startp - 1) == '\n'))
+	   || (pointm == startp &&
+	       EQ (Fmarker_buffer (w->last_start[CURRENT_DISP]), w->buffer) &&
+	       startp < marker_position (w->last_start[CURRENT_DISP]))
+	   || (startp == BUF_ZV (b)))
+    {
+      startp = regenerate_window_point_center (w, pointm, DESIRED_DISP);
+
+      goto regeneration_done;
+    }
+  /* See if we can update the data structures locally based on
+     knowledge of what changed in the buffer. */
+  else if (!w->windows_changed
+	   && !f->clip_changed
+	   && !f->faces_changed
+	   && !f->glyphs_changed
+	   && !f->subwindows_changed
+	   && !f->subwindows_state_changed
+	   && !f->windows_structure_changed
+	   && !f->frame_changed
+	   && !truncation_changed
+	   && pointm >= startp
+	   && regenerate_window_incrementally (w, startp, pointm))
+    {
+      if (f->modeline_changed
+	  || XINT (w->last_modified[CURRENT_DISP]) < BUF_MODIFF (b)
+	  || XINT (w->last_facechange[CURRENT_DISP]) < BUF_FACECHANGE (b))
+	regenerate_modeline (w);
+
+      skip_output = 1;
+      goto regeneration_done;
+    }
+  /* #### This is where a check for structure based scrolling would go. */
+  /* If all else fails, try just regenerating and see what happens. */
+  else
+    {
+      regenerate_window (w, startp, pointm, DESIRED_DISP);
+
+      if (point_visible (w, pointm, DESIRED_DISP))
+	goto regeneration_done;
+    }
+
+  /* We still haven't gotten the window regenerated with point
+     visible.  Next we try scrolling a little and see if point comes
+     back onto the screen. */
+  if (scroll_step > 0)
+    {
+      int scrolled = scroll_conservatively;
+      for (; scrolled >= 0; scrolled -= scroll_step)
+	{
+	  startp = vmotion (w, startp,
+			    (pointm < startp) ? -scroll_step : scroll_step, 0);
+	  regenerate_window (w, startp, pointm, DESIRED_DISP);
+
+	  if (point_visible (w, pointm, DESIRED_DISP))
+	    goto regeneration_done;
+	}
+    }
+
+  /* We still haven't managed to get the screen drawn with point on
+     the screen, so just center it and be done with it. */
+  startp = regenerate_window_point_center (w, pointm, DESIRED_DISP);
+
+
+regeneration_done:
+
+  /* If the window's frame is changed then reset the current display
+     lines in order to force a full repaint. */
+  if (f->frame_changed)
+    {
+      display_line_dynarr *cla = window_display_lines (w, CURRENT_DISP);
+
+      Dynarr_reset (cla);
+    }
+
+  /* Must do this before calling redisplay_output_window because it
+     sets some markers on the window. */
+  if (echo_active)
+    {
+      w->buffer = old_buffer;
+      Fset_marker (w->pointm[DESIRED_DISP], make_int (old_pointm), old_buffer);
+      Fset_marker (w->start[DESIRED_DISP], make_int (old_startp), old_buffer);
+    }
+
+  /* These also have to be set before calling redisplay_output_window
+     since it sets the CURRENT_DISP values based on them. */
+  w->last_modified[DESIRED_DISP] = make_int (BUF_MODIFF (b));
+  w->last_facechange[DESIRED_DISP] = make_int (BUF_FACECHANGE (b));
+  Fset_marker (w->last_start[DESIRED_DISP], make_int (startp), w->buffer);
+  Fset_marker (w->last_point[DESIRED_DISP], make_int (pointm), w->buffer);
+
+  if (!skip_output)
+    {
+      Bufpos start = marker_position (w->start[DESIRED_DISP]);
+      Bufpos end = (w->window_end_pos[DESIRED_DISP] == -1
+		    ? BUF_ZV (b)
+		    : BUF_Z (b) - w->window_end_pos[DESIRED_DISP] - 1);
+      /* Don't pollute the cache if not sure if we are correct */
+      if (w->start_at_line_beg)
+	update_line_start_cache (w, start, end, pointm, 1);
+      redisplay_output_window (w);
+      /*
+       * If we just displayed the echo area, the line start cache is
+       * no longer valid, because the minibuffer window is associated
+       * with the window now.
+       */
+      if (echo_active)
+	w->line_cache_last_updated = make_int (-1);
+    }
+
+  /* #### This should be dependent on face changes and will need to be
+     somewhere else once tty updates occur on a per-frame basis. */
+  mark_face_cachels_as_clean (w);
+
+  /* The glyph cachels only get dirty if someone changed something. */
+  if (glyphs_changed)
+    mark_glyph_cachels_as_clean (w);
+
+  w->windows_changed = 0;
+}
+
+/* Call buffer_reset_changes for all buffers present in any window
+   currently visible in all frames on all devices.  #### There has to
+   be a better way to do this. */
+
+static int
+reset_buffer_changes_mapfun (struct window *w, void *ignored_closure)
+{
+  buffer_reset_changes (XBUFFER (w->buffer));
+  return 0;
+}
+
+static void
+reset_buffer_changes (void)
+{
+  Lisp_Object frmcons, devcons, concons;
+
+  FRAME_LOOP_NO_BREAK (frmcons, devcons, concons)
+    {
+      struct frame *f = XFRAME (XCAR (frmcons));
+
+      if (FRAME_REPAINT_P (f))
+	map_windows (f, reset_buffer_changes_mapfun, 0);
+    }
+}
+
+/* Ensure that all windows underneath the given window in the window
+   hierarchy are correctly displayed. */
+
+static void
+redisplay_windows (Lisp_Object window, int skip_selected)
+{
+  for (; !NILP (window) ; window = XWINDOW (window)->next)
+    {
+      redisplay_window (window, skip_selected);
+    }
+}
+
+static int
+call_redisplay_end_triggers (struct window *w, void *closure)
+{
+  Bufpos lrpos = w->last_redisplay_pos;
+  w->last_redisplay_pos = 0;
+  if (!NILP (w->buffer)
+      && !NILP (w->redisplay_end_trigger)
+      && lrpos > 0)
+    {
+      Bufpos pos;
+
+      if (MARKERP (w->redisplay_end_trigger)
+	  && XMARKER (w->redisplay_end_trigger)->buffer != 0)
+	pos = marker_position (w->redisplay_end_trigger);
+      else if (INTP (w->redisplay_end_trigger))
+	pos = XINT (w->redisplay_end_trigger);
+      else
+	{
+	  w->redisplay_end_trigger = Qnil;
+	  return 0;
+	}
+
+      if (lrpos >= pos)
+	{
+	  Lisp_Object window;
+	  XSETWINDOW (window, w);
+	  va_run_hook_with_args_in_buffer (XBUFFER (w->buffer),
+					   Qredisplay_end_trigger_functions,
+					   2, window,
+					   w->redisplay_end_trigger);
+	  w->redisplay_end_trigger = Qnil;
+	}
+    }
+
+  return 0;
+}
+
+/* Ensure that all windows on the given frame are correctly displayed. */
+
+static int
+redisplay_frame (struct frame *f, int preemption_check)
+{
+  struct device *d = XDEVICE (f->device);
+
+  if (preemption_check)
+    {
+      /* The preemption check itself takes a lot of time,
+	 so normally don't do it here.  We do it if called
+	 from Lisp, though (`redisplay-frame'). */
+      int preempted;
+
+      REDISPLAY_PREEMPTION_CHECK;
+      if (preempted)
+	return 1;
+    }
+
+  /* Before we put a hold on frame size changes, attempt to process
+     any which are already pending. */
+  if (f->size_change_pending)
+    change_frame_size (f, f->new_height, f->new_width, 0);
+
+  /* If frame size might need to be changed, due to changed size
+     of toolbars, scrollbars etc, change it now */
+  if (f->size_slipped)
+    {
+      adjust_frame_size (f);
+      assert (!f->size_slipped);
+    }
+
+  /* The menubar, toolbar, and icon updates must be done before
+     hold_frame_size_changes is called and we are officially
+     'in_display'.  They may eval lisp code which may call Fsignal.
+     If in_display is set Fsignal will abort. */
+
+#ifdef HAVE_MENUBARS
+  /* Update the menubar.  It is done first since it could change
+     the menubar's visibility.  This way we avoid having flashing
+     caused by an Expose event generated by the visibility change
+     being handled. */
+  update_frame_menubars (f);
+#endif /* HAVE_MENUBARS */
+  /* widgets are similar to menus in that they can call lisp to
+     determine activation etc. Therefore update them before we get
+     into redisplay. This is primarily for connected widgets such as
+     radio buttons. */
+  update_frame_subwindows (f);
+#ifdef HAVE_TOOLBARS
+  /* Update the toolbars. */
+  update_frame_toolbars (f);
+#endif /* HAVE_TOOLBARS */
+
+  /* If we clear the frame we have to force its contents to be redrawn. */
+  if (f->clear)
+    f->frame_changed = 1;
+
+  /* invalidate the subwindow cache. We use subwindows_changed here to
+     cause subwindows to get instantiated. This is because
+     subwindows_state_changed is less strict - dealing with things
+     like the clicked state of button. We have to do this before
+     redisplaying the gutters as subwindows get unmapped in the
+     process.*/
+  if (!Dynarr_length (f->subwindow_cachels)
+      || f->subwindows_changed
+      || f->frame_changed)
+    {
+      reset_subwindow_cachels (f);
+      /* we have to do this so the gutter gets regenerated. */
+      reset_gutter_display_lines (f);
+    }
+  else
+    mark_subwindow_cachels_as_not_updated (f);
+  /* We can now update the gutters, safe in the knowledge that our
+     efforts won't get undone. */
+  update_frame_gutters (f);
+
+  hold_frame_size_changes ();
+
+  /* ----------------- BEGIN CRITICAL REDISPLAY SECTION ---------------- */
+  /* Within this section, we are defenseless and assume that the
+     following cannot happen:
+
+     1) garbage collection
+     2) Lisp code evaluation
+     3) frame size changes
+
+     We ensure (3) by calling hold_frame_size_changes(), which
+     will cause any pending frame size changes to get put on hold
+     till after the end of the critical section.  (1) follows
+     automatically if (2) is met.  #### Unfortunately, there are
+     some places where Lisp code can be called within this section.
+     We need to remove them.
+
+     If Fsignal() is called during this critical section, we
+     will abort().
+
+     If garbage collection is called during this critical section,
+     we simply return. #### We should abort instead.
+
+     #### If a frame-size change does occur we should probably
+     actually be preempting redisplay. */
+
+  /* Erase the frame before outputting its contents. */
+  if (f->clear)
+    {
+      DEVMETH (d, clear_frame, (f));
+    }
+
+  /* Do the selected window first. */
+  redisplay_window (FRAME_SELECTED_WINDOW (f), 0);
+
+  /* Then do the rest. */
+  redisplay_windows (f->root_window, 1);
+
+  /* We now call the output_end routine for tty frames.  We delay
+     doing so in order to avoid cursor flicker.  So much for 100%
+     encapsulation. */
+  if (FRAME_TTY_P (f))
+    DEVMETH (d, output_end, (d));
+
+  update_frame_title (f);
+
+  CLASS_RESET_CHANGED_FLAGS (f);
+  f->window_face_cache_reset = 0;
+  f->echo_area_garbaged = 0;
+  f->clear = 0;
+
+  if (!f->size_change_pending)
+    f->size_changed = 0;
+
+  /* ----------------- END CRITICAL REDISPLAY SECTION ---------------- */
+
+  /* Allow frame size changes to occur again.
+
+     #### what happens if changes to other frames happen? */
+  unhold_one_frame_size_changes (f);
+
+  map_windows (f, call_redisplay_end_triggers, 0);
+  return 0;
+}
+
+/* Ensure that all frames on the given device are correctly displayed. */
+
+static int
+redisplay_device (struct device *d)
+{
+  Lisp_Object frame, frmcons;
+  int preempted = 0;
+  int size_change_failed = 0;
+  struct frame *f;
+
+  if (DEVICE_STREAM_P (d)) /* nothing to do */
+    return 0;
+
+  /* It is possible that redisplay has been called before the
+     device is fully initialized.  If so then continue with the
+     next device. */
+  if (NILP (DEVICE_SELECTED_FRAME (d)))
+    return 0;
+
+  REDISPLAY_PREEMPTION_CHECK;
+  if (preempted)
+    return 1;
+
+  /* Always do the selected frame first. */
+  frame = DEVICE_SELECTED_FRAME (d);
+
+  f = XFRAME (frame);
+
+  if (f->icon_changed || f->windows_changed)
+    update_frame_icon (f);
+
+  if (FRAME_REPAINT_P (f))
+    {
+      if (CLASS_REDISPLAY_FLAGS_CHANGEDP(f))
+	{
+	  preempted = redisplay_frame (f, 0);
+	}
+
+      if (preempted)
+	return 1;
+
+      /* If the frame redisplay did not get preempted, then this flag
+         should have gotten set to 0.  It might be possible for that
+         not to happen if a size change event were to occur at an odd
+         time.  To make sure we don't miss anything we simply don't
+         reset the top level flags until the condition ends up being
+         in the right state. */
+      if (f->size_changed)
+	size_change_failed = 1;
+    }
+
+  DEVICE_FRAME_LOOP (frmcons, d)
+    {
+      f = XFRAME (XCAR (frmcons));
+
+      if (f == XFRAME (DEVICE_SELECTED_FRAME (d)))
+	continue;
+
+      if (f->icon_changed || f->windows_changed)
+	update_frame_icon (f);
+
+      if (FRAME_REPAINT_P (f))
+	{
+	  if (CLASS_REDISPLAY_FLAGS_CHANGEDP(f)
+	      || f->size_changed)
+	    {
+	      preempted = redisplay_frame (f, 0);
+	    }
+
+	  if (preempted)
+	    return 1;
+
+	  if (f->size_change_pending)
+	    size_change_failed = 1;
+	}
+    }
+
+  /* If we get here then we redisplayed all of our frames without
+     getting preempted so mark ourselves as clean. */
+  CLASS_RESET_CHANGED_FLAGS (d);
+
+  if (!size_change_failed)
+    d->size_changed = 0;
+
+  return 0;
+}
+
+static Lisp_Object
+restore_profiling_redisplay_flag (Lisp_Object val)
+{
+  profiling_redisplay_flag = XINT (val);
+  return Qnil;
+}
+
+/* Ensure that all windows on all frames on all devices are displaying
+   the current contents of their respective buffers. */
+
+static void
+redisplay_without_hooks (void)
+{
+  Lisp_Object devcons, concons;
+  int size_change_failed = 0;
+  int count = specpdl_depth ();
+
+  if (profiling_active)
+    {
+      record_unwind_protect (restore_profiling_redisplay_flag,
+			     make_int (profiling_redisplay_flag));
+      profiling_redisplay_flag = 1;
+    }
+
+  if (asynch_device_change_pending)
+    handle_asynch_device_change ();
+
+  if (!GLOBAL_REDISPLAY_FLAGS_CHANGEDP &&
+    !size_changed && !disable_preemption && preemption_count < max_preempts)
+    goto done;
+
+  DEVICE_LOOP_NO_BREAK (devcons, concons)
+    {
+      struct device *d = XDEVICE (XCAR (devcons));
+      int preempted;
+
+      if (CLASS_REDISPLAY_FLAGS_CHANGEDP (d)
+	  || d->size_changed)
+	{
+	  preempted = redisplay_device (d);
+
+	  if (preempted)
+	    {
+	      preemption_count++;
+	      RESET_CHANGED_SET_FLAGS;
+	      goto done;
+	    }
+
+	  /* See comment in redisplay_device. */
+	  if (d->size_changed)
+	    size_change_failed = 1;
+	}
+    }
+  preemption_count = 0;
+
+  /* Mark redisplay as accurate */
+  GLOBAL_RESET_CHANGED_FLAGS;
+  RESET_CHANGED_SET_FLAGS;
+
+  if (faces_changed)
+    {
+      mark_all_faces_as_clean ();
+      faces_changed = 0;
+    }
+
+  if (!size_change_failed)
+    size_changed = 0;
+
+  reset_buffer_changes ();
+
+ done:
+  unbind_to (count, Qnil);
+}
+
+void
+redisplay (void)
+{
+  if (last_display_warning_tick != display_warning_tick &&
+      !inhibit_warning_display)
+    {
+      /* If an error occurs during this function, oh well.
+         If we report another warning, we could get stuck in an
+	 infinite loop reporting warnings. */
+      call0_trapping_errors (0, Qdisplay_warning_buffer);
+      last_display_warning_tick = display_warning_tick;
+    }
+  /* The run_hook_trapping_errors functions are smart enough not
+     to do any evalling if the hook function is empty, so there
+     should not be any significant time loss.  All places in the
+     C code that call redisplay() are prepared to handle GCing,
+     so we should be OK. */
+#ifndef INHIBIT_REDISPLAY_HOOKS
+  run_hook_trapping_errors ("Error in pre-redisplay-hook",
+			    Qpre_redisplay_hook);
+#endif /* INHIBIT_REDISPLAY_HOOKS */
+
+  redisplay_without_hooks ();
+
+#ifndef INHIBIT_REDISPLAY_HOOKS
+  run_hook_trapping_errors ("Error in post-redisplay-hook",
+			    Qpost_redisplay_hook);
+#endif /* INHIBIT_REDISPLAY_HOOKS */
+}
+
+
+static char window_line_number_buf[32];
+
+/* Efficiently determine the window line number, and return a pointer
+   to its printed representation.  Do this regardless of whether
+   line-number-mode is on.  The first line in the buffer is counted as
+   1.  If narrowing is in effect, the lines are counted from the
+   beginning of the visible portion of the buffer.  */
+static char *
+window_line_number (struct window *w, int type)
+{
+  struct device *d = XDEVICE (XFRAME (w->frame)->device);
+  struct buffer *b = XBUFFER (w->buffer);
+  /* Be careful in the order of these tests. The first clause will
+     fail if DEVICE_SELECTED_FRAME == Qnil (since w->frame cannot be).
+     This can occur when the frame title is computed really early */
+  Bufpos pos =
+    ((EQ(DEVICE_SELECTED_FRAME(d), w->frame) &&
+       (w == XWINDOW (FRAME_SELECTED_WINDOW (device_selected_frame(d)))) &&
+      EQ(DEVICE_CONSOLE(d), Vselected_console) &&
+      XDEVICE(CONSOLE_SELECTED_DEVICE(XCONSOLE(DEVICE_CONSOLE(d)))) == d )
+     ? BUF_PT (b)
+     : marker_position (w->pointm[type]));
+  EMACS_INT line;
+
+  line = buffer_line_number (b, pos, 1);
+
+  long_to_string (window_line_number_buf, line + 1);
+
+  return window_line_number_buf;
+}
+
+
+/* Given a character representing an object in a modeline
+   specification, return a string (stored into the global array
+   `mode_spec_bufbyte_string') with the information that object
+   represents.
+
+   This function is largely unchanged from previous versions of the
+   redisplay engine.
+
+   Warning! This code is also used for frame titles and can be called
+   very early in the device/frame update process!  JV
+*/
+
+static void
+decode_mode_spec (struct window *w, Emchar spec, int type)
+{
+  Lisp_Object obj = Qnil;
+  CONST char *str = NULL;
+  struct buffer *b = XBUFFER (w->buffer);
+
+  Dynarr_reset (mode_spec_bufbyte_string);
+
+  switch (spec)
+    {
+      /* print buffer name */
+    case 'b':
+      obj = b->name;
+      break;
+
+      /* print visited file name */
+    case 'f':
+      obj = b->filename;
+      break;
+
+      /* print the current column */
+    case 'c':
+      {
+        Bufpos pt = (w == XWINDOW (Fselected_window (Qnil)))
+                    ? BUF_PT (b)
+                    : marker_position (w->pointm[type]);
+	int col = column_at_point (b, pt, 1) + !!column_number_start_at_one;
+	char buf[32];
+
+	long_to_string (buf, col);
+
+	Dynarr_add_many (mode_spec_bufbyte_string,
+			 (CONST Bufbyte *) buf, strlen (buf));
+
+	goto decode_mode_spec_done;
+      }
+      /* print the file coding system */
+    case 'C':
+#ifdef FILE_CODING
+      {
+        Lisp_Object codesys = b->buffer_file_coding_system;
+        /* Be very careful here not to get an error. */
+	if (NILP (codesys) || SYMBOLP (codesys) || CODING_SYSTEMP (codesys))
+          {
+            codesys = Ffind_coding_system (codesys);
+	    if (CODING_SYSTEMP (codesys))
+              obj = XCODING_SYSTEM_MNEMONIC (codesys);
+          }
+      }
+#endif /* FILE_CODING */
+      break;
+
+      /* print the current line number */
+    case 'l':
+      str = window_line_number (w, type);
+      break;
+
+      /* print value of mode-name (obsolete) */
+    case 'm':
+      obj = b->mode_name;
+      break;
+
+      /* print hyphen and frame number, if != 1 */
+    case 'N':
+#ifdef HAVE_TTY
+      {
+	struct frame *f = XFRAME (w->frame);
+	if (FRAME_TTY_P (f) && f->order_count > 1 && f->order_count <= 99999999)
+	  {
+	    /* Naughty, naughty */
+	    char * writable_str = alloca_array (char, 10);
+	    sprintf (writable_str, "-%d", f->order_count);
+	    str = writable_str;
+	  }
+      }
+#endif /* HAVE_TTY */
+      break;
+
+      /* print Narrow if appropriate */
+    case 'n':
+      if (BUF_BEGV (b) > BUF_BEG (b)
+	  || BUF_ZV (b) < BUF_Z (b))
+	str = " Narrow";
+      break;
+
+      /* print %, * or hyphen, if buffer is read-only, modified or neither */
+    case '*':
+      str = (!NILP (b->read_only)
+	     ? "%"
+	     : ((BUF_MODIFF (b) > BUF_SAVE_MODIFF (b))
+		? "*"
+		: "-"));
+      break;
+
+      /* print * or hyphen -- XEmacs change to allow a buffer to be
+         read-only but still indicate whether it is modified. */
+    case '+':
+      str = ((BUF_MODIFF (b) > BUF_SAVE_MODIFF (b))
+	     ? "*"
+	     : (!NILP (b->read_only)
+		? "%"
+		: "-"));
+      break;
+
+      /* #### defined in 19.29 decode_mode_spec, but not in
+         modeline-format doc string. */
+      /* This differs from %* in that it ignores read-only-ness. */
+    case '&':
+      str = ((BUF_MODIFF (b) > BUF_SAVE_MODIFF (b))
+	     ? "*"
+	     : "-");
+      break;
+
+      /* print process status */
+    case 's':
+      obj = Fget_buffer_process (w->buffer);
+      if (NILP (obj))
+	str = GETTEXT ("no process");
+      else
+	obj = Fsymbol_name (Fprocess_status (obj));
+      break;
+
+      /* Print name of selected frame.  */
+    case 'S':
+      obj = XFRAME (w->frame)->name;
+      break;
+
+      /* indicate TEXT or BINARY */
+    case 't':
+      /* #### NT does not use this any more. Now what? */
+      str = "T";
+      break;
+
+      /* print percent of buffer above top of window, or Top, Bot or All */
+    case 'p':
+    {
+      Bufpos pos = marker_position (w->start[type]);
+
+      /* This had better be while the desired lines are being done. */
+      if (w->window_end_pos[type] <= BUF_Z (b) - BUF_ZV (b))
+	{
+	  if (pos <= BUF_BEGV (b))
+	    str = "All";
+	  else
+	    str = "Bottom";
+	}
+      else if (pos <= BUF_BEGV (b))
+	str = "Top";
+      else
+	{
+	  /* This hard limit is ok since the string it will hold has a
+             fixed maximum length of 3.  But just to be safe... */
+	  char buf[10];
+	  Charcount chars = pos - BUF_BEGV (b);
+	  Charcount total = BUF_ZV (b) - BUF_BEGV (b);
+
+	  /* Avoid overflow on big buffers */
+	  int percent = total > LONG_MAX/200 ?
+	    (chars + total/200) / (total / 100) :
+	    (chars * 100 + total/2) / total;
+
+	  /* We can't normally display a 3-digit number, so get us a
+             2-digit number that is close. */
+	  if (percent == 100)
+	    percent = 99;
+
+	  sprintf (buf, "%d%%", percent);
+	  Dynarr_add_many (mode_spec_bufbyte_string, (Bufbyte *) buf,
+			   strlen (buf));
+
+	  goto decode_mode_spec_done;
+	}
+      break;
+    }
+
+    /* print percent of buffer above bottom of window, perhaps plus
+       Top, or print Bottom or All */
+    case 'P':
+    {
+      Bufpos toppos = marker_position (w->start[type]);
+      Bufpos botpos = BUF_Z (b) - w->window_end_pos[type];
+
+      /* botpos is only accurate as of the last redisplay, so we can
+         only treat it as a hint.  In particular, after erase-buffer,
+         botpos may be negative. */
+      if (botpos < toppos)
+	botpos = toppos;
+
+      if (botpos >= BUF_ZV (b))
+	{
+	  if (toppos <= BUF_BEGV (b))
+	    str = "All";
+	  else
+	    str = "Bottom";
+	}
+      else
+	{
+	  /* This hard limit is ok since the string it will hold has a
+             fixed maximum length of around 6.  But just to be safe... */
+	  char buf[10];
+	  Charcount chars = botpos - BUF_BEGV (b);
+	  Charcount total = BUF_ZV (b) - BUF_BEGV (b);
+
+	  /* Avoid overflow on big buffers */
+	  int percent = total > LONG_MAX/200 ?
+	    (chars + total/200) / (total / 100) :
+	    (chars * 100 + total/2) / max (total, 1);
+
+	  /* We can't normally display a 3-digit number, so get us a
+             2-digit number that is close. */
+	  if (percent == 100)
+	    percent = 99;
+
+	  if (toppos <= BUF_BEGV (b))
+	    sprintf (buf, "Top%d%%", percent);
+	  else
+	    sprintf (buf, "%d%%", percent);
+
+	  Dynarr_add_many (mode_spec_bufbyte_string, (Bufbyte *) buf,
+			   strlen (buf));
+
+	  goto decode_mode_spec_done;
+	}
+      break;
+    }
+
+    /* print % */
+    case '%':
+      str = "%";
+      break;
+
+      /* print one [ for each recursive editing level. */
+    case '[':
+    {
+      int i;
+
+      if (command_loop_level > 5)
+	{
+	  str = "[[[... ";
+	  break;
+	}
+
+      for (i = 0; i < command_loop_level; i++)
+	Dynarr_add (mode_spec_bufbyte_string, '[');
+
+      goto decode_mode_spec_done;
+    }
+
+    /* print one ] for each recursive editing level. */
+    case ']':
+    {
+      int i;
+
+      if (command_loop_level > 5)
+	{
+	  str = "...]]]";
+	  break;
+	}
+
+      for (i = 0; i < command_loop_level; i++)
+	Dynarr_add (mode_spec_bufbyte_string, ']');
+
+      goto decode_mode_spec_done;
+    }
+
+    /* print infinitely many dashes -- handle at top level now */
+    case '-':
+      break;
+
+    }
+
+  if (STRINGP (obj))
+    Dynarr_add_many (mode_spec_bufbyte_string,
+		     XSTRING_DATA   (obj),
+		     XSTRING_LENGTH (obj));
+  else if (str)
+    Dynarr_add_many (mode_spec_bufbyte_string, (Bufbyte *) str, strlen (str));
+
+decode_mode_spec_done:
+  Dynarr_add (mode_spec_bufbyte_string, '\0');
+}
+
+/* Given a display line, free all of its data structures. */
+
+static void
+free_display_line (struct display_line *dl)
+{
+  int block;
+
+  if (dl->display_blocks)
+    {
+      for (block = 0; block < Dynarr_largest (dl->display_blocks); block++)
+	{
+	  struct display_block *db = Dynarr_atp (dl->display_blocks, block);
+
+	  Dynarr_free (db->runes);
+	}
+
+      Dynarr_free (dl->display_blocks);
+      dl->display_blocks = NULL;
+    }
+
+  if (dl->left_glyphs)
+    {
+      Dynarr_free (dl->left_glyphs);
+      dl->left_glyphs = NULL;
+    }
+
+  if (dl->right_glyphs)
+    {
+      Dynarr_free (dl->right_glyphs);
+      dl->right_glyphs = NULL;
+    }
+}
+
+
+/* Given an array of display lines, free them and all data structures
+   contained within them. */
+
+void
+free_display_lines (display_line_dynarr *dla)
+{
+  int line;
+
+  for (line = 0; line < Dynarr_largest (dla); line++)
+    {
+      free_display_line (Dynarr_atp (dla, line));
+    }
+
+  Dynarr_free (dla);
+}
+
+/* Call internal free routine for each set of display lines. */
+
+void
+free_display_structs (struct window_mirror *mir)
+{
+  if (mir->current_display_lines)
+    {
+      free_display_lines (mir->current_display_lines);
+      mir->current_display_lines = 0;
+    }
+
+  if (mir->desired_display_lines)
+    {
+      free_display_lines (mir->desired_display_lines);
+      mir->desired_display_lines = 0;
+    }
+}
+
+
+static void
+mark_glyph_block_dynarr (glyph_block_dynarr *gba)
+{
+  if (gba)
+    {
+      glyph_block *gb = Dynarr_atp (gba, 0);
+      glyph_block *gb_last = Dynarr_atp (gba, Dynarr_length (gba));
+
+      for (; gb < gb_last; gb++)
+	{
+	  if (!NILP (gb->glyph))
+	    mark_object (gb->glyph);
+	  if (!NILP (gb->extent))
+	    mark_object (gb->extent);
+	}
+    }
+}
+
+static void
+mark_redisplay_structs (display_line_dynarr *dla)
+{
+  display_line *dl = Dynarr_atp (dla, 0);
+  display_line *dl_last = Dynarr_atp (dla, Dynarr_length (dla));
+
+  for (; dl < dl_last; dl++)
+    {
+      display_block_dynarr *dba = dl->display_blocks;
+      display_block *db = Dynarr_atp (dba, 0);
+      display_block *db_last = Dynarr_atp (dba, Dynarr_length (dba));
+
+      for (; db < db_last; db++)
+	{
+	  rune_dynarr *ra = db->runes;
+	  rune *r = Dynarr_atp (ra, 0);
+	  rune *r_last = Dynarr_atp (ra, Dynarr_length (ra));
+
+	  for (; r < r_last; r++)
+	    {
+	      if (r->type == RUNE_DGLYPH)
+		{
+		  if (!NILP (r->object.dglyph.glyph))
+		    mark_object (r->object.dglyph.glyph);
+		  if (!NILP (r->object.dglyph.extent))
+		    mark_object (r->object.dglyph.extent);
+		}
+	    }
+	}
+
+      mark_glyph_block_dynarr (dl->left_glyphs);
+      mark_glyph_block_dynarr (dl->right_glyphs);
+    }
+}
+
+static void
+mark_window_mirror (struct window_mirror *mir)
+{
+  mark_redisplay_structs (mir->current_display_lines);
+  mark_redisplay_structs (mir->desired_display_lines);
+
+  if (mir->next)
+    mark_window_mirror (mir->next);
+
+  if (mir->hchild)
+    mark_window_mirror (mir->hchild);
+  else if (mir->vchild)
+    mark_window_mirror (mir->vchild);
+}
+
+void
+mark_redisplay (void)
+{
+  Lisp_Object frmcons, devcons, concons;
+
+  FRAME_LOOP_NO_BREAK (frmcons, devcons, concons)
+    {
+      struct frame *f = XFRAME (XCAR (frmcons));
+      update_frame_window_mirror (f);
+      mark_window_mirror (f->root_mirror);
+    }
+}
+
+/*****************************************************************************
+ Line Start Cache Description and Rationale
+
+ The traditional scrolling code in Emacs breaks in a variable height world.
+ It depends on the key assumption that the number of lines that can be
+ displayed at any given time is fixed.  This led to a complete separation
+ of the scrolling code from the redisplay code.  In order to fully support
+ variable height lines, the scrolling code must actually be tightly
+ integrated with redisplay.  Only redisplay can determine how many lines
+ will be displayed on a screen for any given starting point.
+
+ What is ideally wanted is a complete list of the starting buffer position
+ for every possible display line of a buffer along with the height of that
+ display line.  Maintaining such a full list would be very expensive.  We
+ settle for having it include information for all areas which we happen to
+ generate anyhow (i.e. the region currently being displayed) and for those
+ areas we need to work with.
+
+ In order to ensure that the cache accurately represents what redisplay
+ would actually show, it is necessary to invalidate it in many situations.
+ If the buffer changes, the starting positions may no longer be correct.
+ If a face or an extent has changed then the line heights may have altered.
+ These events happen frequently enough that the cache can end up being
+ constantly disabled.  With this potentially constant invalidation when is
+ the cache ever useful?
+
+ Even if the cache is invalidated before every single usage, it is
+ necessary.  Scrolling often requires knowledge about display lines which
+ are actually above or below the visible region.  The cache provides a
+ convenient light-weight method of storing this information for multiple
+ display regions.  This knowledge is necessary for the scrolling code to
+ always obey the First Golden Rule of Redisplay.
+
+ If the cache already contains all of the information that the scrolling
+ routines happen to need so that it doesn't have to go generate it, then we
+ are able to obey the Third Golden Rule of Redisplay.  The first thing we
+ do to help out the cache is to always add the displayed region.  This
+ region had to be generated anyway, so the cache ends up getting the
+ information basically for free.  In those cases where a user is simply
+ scrolling around viewing a buffer there is a high probability that this is
+ sufficient to always provide the needed information.  The second thing we
+ can do is be smart about invalidating the cache.
+
+ TODO -- Be smart about invalidating the cache.  Potential places:
+
+ + Insertions at end-of-line which don't cause line-wraps do not alter the
+   starting positions of any display lines.  These types of buffer
+   modifications should not invalidate the cache.  This is actually a large
+   optimization for redisplay speed as well.
+
+ + Buffer modifications frequently only affect the display of lines at and
+   below where they occur.  In these situations we should only invalidate
+   the part of the cache starting at where the modification occurs.
+
+ In case you're wondering, the Second Golden Rule of Redisplay is not
+ applicable.
+ ****************************************************************************/
+
+/* This will get used quite a bit so we don't want to be constantly
+   allocating and freeing it. */
+static line_start_cache_dynarr *internal_cache;
+
+/* Makes internal_cache represent the TYPE display structs and only
+   the TYPE display structs. */
+
+static void
+update_internal_cache_list (struct window *w, int type)
+{
+  int line;
+  display_line_dynarr *dla = window_display_lines (w, type);
+
+  Dynarr_reset (internal_cache);
+  for (line = 0; line < Dynarr_length (dla); line++)
+    {
+      struct display_line *dl = Dynarr_atp (dla, line);
+
+      if (dl->modeline)
+	continue;
+      else
+	{
+	  struct line_start_cache lsc;
+	  
+	  lsc.start = dl->bufpos;
+	  lsc.end = dl->end_bufpos;
+	  lsc.height = dl->ascent + dl->descent;
+
+	  Dynarr_add (internal_cache, lsc);
+	}
+    }
+}
+
+/* Reset the line cache if necessary.  This should be run at the
+   beginning of any function which access the cache. */
+
+static void
+validate_line_start_cache (struct window *w)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  struct frame *f = XFRAME (w->frame);
+
+  if (!w->line_cache_validation_override)
+    {
+      /* f->extents_changed used to be in here because extent face and
+         size changes can cause text shifting.  However, the extent
+         covering the region is constantly having its face set and
+         priority altered by the mouse code.  This means that the line
+         start cache is constantly being invalidated.  This is bad
+         since the mouse code also triggers heavy usage of the cache.
+         Since it is an unlikely that f->extents being changed
+         indicates that the cache really needs to be updated and if it
+         does redisplay will catch it pretty quickly we no longer
+         invalidate the cache if it is set.  This greatly speeds up
+         dragging out regions with the mouse. */
+      if (XINT (w->line_cache_last_updated) < BUF_MODIFF (b)
+	  || f->faces_changed
+	  || f->clip_changed)
+	{
+	  Dynarr_reset (w->line_start_cache);
+	}
+    }
+}
+
+/* Return the very first buffer position contained in the given
+   window's cache, or -1 if the cache is empty.  Assumes that the
+   cache is valid. */
+
+static Bufpos
+line_start_cache_start (struct window *w)
+{
+  line_start_cache_dynarr *cache = w->line_start_cache;
+
+  if (!Dynarr_length (cache))
+    return -1;
+  else
+    return Dynarr_atp (cache, 0)->start;
+}
+
+/* Return the very last buffer position contained in the given
+   window's cache, or -1 if the cache is empty.  Assumes that the
+   cache is valid. */
+
+static Bufpos
+line_start_cache_end (struct window *w)
+{
+  line_start_cache_dynarr *cache = w->line_start_cache;
+
+  if (!Dynarr_length (cache))
+    return -1;
+  else
+    return Dynarr_atp (cache, Dynarr_length (cache) - 1)->end;
+}
+
+/* Return the index of the line POINT is contained within in window
+   W's line start cache.  It will enlarge the cache or move the cache
+   window in order to have POINT be present in the cache.  MIN_PAST is
+   a guarantee of the number of entries in the cache present on either
+   side of POINT (unless a buffer boundary is hit).  If MIN_PAST is -1
+   then it will be treated as 0, but the cache window will not be
+   allowed to shift.  Returns -1 if POINT cannot be found in the cache
+   for any reason. */
+
+int
+point_in_line_start_cache (struct window *w, Bufpos point, int min_past)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  line_start_cache_dynarr *cache = w->line_start_cache;
+  unsigned int top, bottom, pos;
+
+  validate_line_start_cache (w);
+  w->line_cache_validation_override++;
+
+  /* Let functions pass in negative values, but we still treat -1
+     specially. */
+  /* #### bogosity alert */
+  if (min_past < 0 && min_past != -1)
+    min_past = -min_past;
+
+  if (!Dynarr_length (cache) || line_start_cache_start (w) > point
+      || line_start_cache_end (w) < point)
+    {
+      int loop;
+      int win_char_height = window_char_height (w, 1);
+
+      /* Occasionally we get here with a 0 height
+         window. find_next_newline_no_quit will abort if we pass it a
+         count of 0 so handle that case. */
+      if (!win_char_height)
+	win_char_height = 1;
+
+      if (!Dynarr_length (cache))
+	{
+	  Bufpos from = find_next_newline_no_quit (b, point, -1);
+	  Bufpos to = find_next_newline_no_quit (b, from, win_char_height);
+
+	  update_line_start_cache (w, from, to, point, 0);
+
+	  if (!Dynarr_length (cache))
+	    {
+	      w->line_cache_validation_override--;
+	      return -1;
+	    }
+	}
+
+      assert (Dynarr_length (cache));
+
+      loop = 0;
+      while (line_start_cache_start (w) > point
+	     && (loop < cache_adjustment || min_past == -1))
+	{
+	  Bufpos from, to;
+
+	  from = line_start_cache_start (w);
+	  if (from <= BUF_BEGV (b))
+	    break;
+
+	  from = find_next_newline_no_quit (b, from, -win_char_height);
+	  to = line_start_cache_end (w);
+
+	  update_line_start_cache (w, from, to, point, 0);
+	  loop++;
+	}
+
+      if (line_start_cache_start (w) > point)
+	{
+	  Bufpos from, to;
+
+	  from = find_next_newline_no_quit (b, point, -1);
+	  if (from >= BUF_ZV (b))
+	    {
+	      to = find_next_newline_no_quit (b, from, -win_char_height);
+	      from = to;
+	      to = BUF_ZV (b);
+	    }
+	  else
+	    to = find_next_newline_no_quit (b, from, win_char_height);
+
+	  update_line_start_cache (w, from, to, point, 0);
+	}
+
+      loop = 0;
+      while (line_start_cache_end (w) < point
+	     && (loop < cache_adjustment || min_past == -1))
+	{
+	  Bufpos from, to;
+
+	  to = line_start_cache_end (w);
+	  if (to >= BUF_ZV (b))
+	    break;
+
+	  from = line_start_cache_end (w);
+	  to = find_next_newline_no_quit (b, from, win_char_height);
+
+	  update_line_start_cache (w, from, to, point, 0);
+	  loop++;
+	}
+
+      if (line_start_cache_end (w) < point)
+	{
+	  Bufpos from, to;
+
+	  from = find_next_newline_no_quit (b, point, -1);
+	  if (from >= BUF_ZV (b))
+	    {
+	      to = find_next_newline_no_quit (b, from, -win_char_height);
+	      from = to;
+	      to = BUF_ZV (b);
+	    }
+	  else
+	    to = find_next_newline_no_quit (b, from, win_char_height);
+
+	  update_line_start_cache (w, from, to, point, 0);
+	}
+    }
+
+  assert (Dynarr_length (cache));
+
+  if (min_past == -1)
+    min_past = 0;
+
+  /* This could happen if the buffer is narrowed. */
+  if (line_start_cache_start (w) > point
+      || line_start_cache_end (w) < point)
+    {
+      w->line_cache_validation_override--;
+      return -1;
+    }
+
+find_point_loop:
+
+  top = Dynarr_length (cache) - 1;
+  bottom = 0;
+
+  while (1)
+    {
+      unsigned int new_pos;
+      Bufpos start, end;
+
+      pos = (bottom + top + 1) >> 1;
+      start = Dynarr_atp (cache, pos)->start;
+      end = Dynarr_atp (cache, pos)->end;
+
+      if (point >= start && point <= end)
+	{
+	  if (pos < min_past && line_start_cache_start (w) > BUF_BEGV (b))
+	    {
+	      Bufpos from =
+		find_next_newline_no_quit (b, line_start_cache_start (w),
+					   -min_past - 1);
+	      Bufpos to = line_start_cache_end (w);
+
+	      update_line_start_cache (w, from, to, point, 0);
+	      goto find_point_loop;
+	    }
+	  else if ((Dynarr_length (cache) - pos - 1) < min_past
+		   && line_start_cache_end (w) < BUF_ZV (b))
+	    {
+	      Bufpos from = line_start_cache_end (w);
+	      Bufpos to = find_next_newline_no_quit (b, from,
+						     (min_past
+						      ? min_past
+						      : 1));
+
+	      update_line_start_cache (w, from, to, point, 0);
+	      goto find_point_loop;
+	    }
+	  else
+	    {
+	      w->line_cache_validation_override--;
+	      return pos;
+	    }
+	}
+      else if (point > end)
+	bottom = pos + 1;
+      else if (point < start)
+	top = pos - 1;
+      else
+	abort ();
+
+      new_pos = (bottom + top + 1) >> 1;
+      if (pos == new_pos)
+	{
+	  w->line_cache_validation_override--;
+	  return -1;
+	}
+    }
+}
+
+/* Return a boolean indicating if POINT would be visible in window W
+   if display of the window was to begin at STARTP. */
+
+int
+point_would_be_visible (struct window *w, Bufpos startp, Bufpos point)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  int pixpos = 0;
+  int bottom = WINDOW_TEXT_HEIGHT (w);
+  int start_elt;
+
+  /* If point is before the intended start it obviously can't be visible. */
+  if (point < startp)
+    return 0;
+
+  /* If point or start are not in the accessible buffer range, then
+     fail. */
+  if (startp < BUF_BEGV (b) || startp > BUF_ZV (b)
+      || point < BUF_BEGV (b) || point > BUF_ZV (b))
+    return 0;
+
+  validate_line_start_cache (w);
+  w->line_cache_validation_override++;
+
+  start_elt = point_in_line_start_cache (w, startp, 0);
+  if (start_elt == -1)
+    {
+      w->line_cache_validation_override--;
+      return 0;
+    }
+
+  assert (line_start_cache_start (w) <= startp
+	  && line_start_cache_end (w) >= startp);
+
+  while (1)
+    {
+      int height;
+
+      /* Expand the cache if necessary. */
+      if (start_elt == Dynarr_length (w->line_start_cache))
+	{
+	  Bufpos old_startp =
+	    Dynarr_atp (w->line_start_cache, start_elt - 1)->start;
+
+	  start_elt = point_in_line_start_cache (w, old_startp,
+						 window_char_height (w, 0));
+
+	  /* We've already actually processed old_startp, so increment
+             immediately. */
+	  start_elt++;
+
+	  /* If this happens we didn't add any extra elements.  Bummer. */
+	  if (start_elt == Dynarr_length (w->line_start_cache))
+	    {
+	      w->line_cache_validation_override--;
+	      return 0;
+	    }
+	}
+
+      height = Dynarr_atp (w->line_start_cache, start_elt)->height;
+
+      if (pixpos + height > bottom)
+	{
+	  if (bottom - pixpos < VERTICAL_CLIP (w, 0))
+	    {
+	      w->line_cache_validation_override--;
+	      return 0;
+	    }
+	}
+
+      pixpos += height;
+      if (point <= Dynarr_atp (w->line_start_cache, start_elt)->end)
+	{
+	  w->line_cache_validation_override--;
+	  return 1;
+	}
+
+      start_elt++;
+    }
+}
+
+/* For the given window W, if display starts at STARTP, what will be
+   the buffer position at the beginning or end of the last line
+   displayed.  The end of the last line is also know as the window end
+   position.
+
+   #### With a little work this could probably be reworked as just a
+   call to start_with_line_at_pixpos. */
+
+static Bufpos
+start_end_of_last_line (struct window *w, Bufpos startp, int end)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  line_start_cache_dynarr *cache = w->line_start_cache;
+  int pixpos = 0;
+  int bottom = WINDOW_TEXT_HEIGHT (w);
+  Bufpos cur_start;
+  int start_elt;
+
+  validate_line_start_cache (w);
+  w->line_cache_validation_override++;
+
+  if (startp < BUF_BEGV (b))
+    startp = BUF_BEGV (b);
+  else if (startp > BUF_ZV (b))
+    startp = BUF_ZV (b);
+  cur_start = startp;
+
+  start_elt = point_in_line_start_cache (w, cur_start, 0);
+  if (start_elt == -1)
+    abort ();	/* this had better never happen */
+
+  while (1)
+    {
+      int height = Dynarr_atp (cache, start_elt)->height;
+
+      cur_start = Dynarr_atp (cache, start_elt)->start;
+
+      if (pixpos + height > bottom)
+	{
+	  /* Adjust for any possible clip. */
+	  if (bottom - pixpos < VERTICAL_CLIP (w, 0))
+	    start_elt--;
+
+	  if (start_elt < 0)
+	    {
+	      w->line_cache_validation_override--;
+	      if (end)
+		return BUF_ZV (b);
+	      else
+		return BUF_BEGV (b);
+	    }
+	  else
+	    {
+	      w->line_cache_validation_override--;
+	      if (end)
+		return Dynarr_atp (cache, start_elt)->end;
+	      else
+		return Dynarr_atp (cache, start_elt)->start;
+	    }
+	}
+
+      pixpos += height;
+      start_elt++;
+      if (start_elt == Dynarr_length (cache))
+	{
+	  Bufpos from = line_start_cache_end (w);
+	  int win_char_height = window_char_height (w, 0);
+	  Bufpos to = find_next_newline_no_quit (b, from,
+						 (win_char_height
+						  ? win_char_height
+						  : 1));
+
+	  /* We've hit the end of the bottom so that's what it is. */
+	  if (from >= BUF_ZV (b))
+	    {
+	      w->line_cache_validation_override--;
+	      return BUF_ZV (b);
+	    }
+
+	  update_line_start_cache (w, from, to, BUF_PT (b), 0);
+
+	  /* Updating the cache invalidates any current indexes. */
+	  start_elt = point_in_line_start_cache (w, cur_start, -1) + 1;
+	}
+    }
+}
+
+/* For the given window W, if display starts at STARTP, what will be
+   the buffer position at the beginning of the last line displayed. */
+
+Bufpos
+start_of_last_line (struct window *w, Bufpos startp)
+{
+  return start_end_of_last_line (w, startp, 0);
+}
+
+/* For the given window W, if display starts at STARTP, what will be
+   the buffer position at the end of the last line displayed.  This is
+   also know as the window end position. */
+
+Bufpos
+end_of_last_line (struct window *w, Bufpos startp)
+{
+  return start_end_of_last_line (w, startp, 1);
+}
+
+/* For window W, what does the starting position have to be so that
+   the line containing POINT will cover pixel position PIXPOS. */
+
+Bufpos
+start_with_line_at_pixpos (struct window *w, Bufpos point, int pixpos)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  int cur_elt;
+  Bufpos cur_pos, prev_pos = point;
+  int point_line_height;
+  int pixheight = pixpos - WINDOW_TEXT_TOP (w);
+
+  validate_line_start_cache (w);
+  w->line_cache_validation_override++;
+
+  cur_elt = point_in_line_start_cache (w, point, 0);
+  /* #### See comment in update_line_start_cache about big minibuffers. */
+  if (cur_elt < 0)
+    {
+      w->line_cache_validation_override--;
+      return point;
+    }
+
+  point_line_height = Dynarr_atp (w->line_start_cache, cur_elt)->height;
+
+  while (1)
+    {
+      cur_pos = Dynarr_atp (w->line_start_cache, cur_elt)->start;
+
+      pixheight -= Dynarr_atp (w->line_start_cache, cur_elt)->height;
+
+      /* Do not take into account the value of vertical_clip here.
+         That is the responsibility of the calling functions. */
+      if (pixheight < 0)
+	{
+	  w->line_cache_validation_override--;
+	  if (-pixheight > point_line_height)
+	    /* We can't make the target line cover pixpos, so put it
+	       above pixpos.  That way it will at least be visible. */
+	    return prev_pos;
+	  else
+	    return cur_pos;
+	}
+
+      cur_elt--;
+      while (cur_elt < 0)
+	{
+	  Bufpos from, to;
+	  int win_char_height;
+
+	  if (cur_pos <= BUF_BEGV (b))
+	    {
+	      w->line_cache_validation_override--;
+	      return BUF_BEGV (b);
+	    }
+
+	  win_char_height = window_char_height (w, 0);
+	  if (!win_char_height)
+	    win_char_height = 1;
+
+	  from = find_next_newline_no_quit (b, cur_pos, -win_char_height);
+	  to = line_start_cache_end (w);
+	  update_line_start_cache (w, from, to, point, 0);
+
+	  cur_elt = point_in_line_start_cache (w, cur_pos, 2) - 1;
+	  assert (cur_elt >= -1);
+	  /* This used to be cur_elt>=0 under the assumption that if
+	     point is in the top line and not at BUF_BEGV, then
+	     setting the window_start to a newline before the start of 
+	     the first line will always cause scrolling.
+
+	     However in my (jv) opinion this is wrong.  That new line
+	     can be hidden in various ways: invisible extents, an
+	     explicit window-start not at a newline character etc.
+	     The existence of those are indeed known to create crashes
+	     on that assert.  So we have no option but to continue the
+	     search if we found point at the top of the line_start_cache
+	     again. */
+	  cur_pos = Dynarr_atp (w->line_start_cache,0)->start;	     
+	}
+      prev_pos = cur_pos;
+    }
+}
+
+/* For window W, what does the starting position have to be so that
+   the line containing point is on display line LINE.  If LINE is
+   positive it is considered to be the number of lines from the top of
+   the window (0 is the top line).  If it is negative the number is
+   considered to be the number of lines from the bottom (-1 is the
+   bottom line). */
+
+Bufpos
+start_with_point_on_display_line (struct window *w, Bufpos point, int line)
+{
+  validate_line_start_cache (w);
+  w->line_cache_validation_override++;
+
+  if (line >= 0)
+    {
+      int cur_elt = point_in_line_start_cache (w, point, line);
+
+      if (cur_elt - line < 0)
+	cur_elt = 0;		/* Hit the top */
+      else
+	cur_elt -= line;
+
+      w->line_cache_validation_override--;
+      return Dynarr_atp (w->line_start_cache, cur_elt)->start;
+    }
+  else
+    {
+      /* The calculated value of pixpos is correct for the bottom line
+         or what we want when line is -1.  Therefore we subtract one
+         because we have already handled one line. */
+      int new_line = -line - 1;
+      int cur_elt = point_in_line_start_cache (w, point, new_line);
+      int pixpos = WINDOW_TEXT_BOTTOM (w);
+      Bufpos retval, search_point;
+
+      /* If scroll_on_clipped_lines is false, the last "visible" line of
+ 	 the window covers the pixel at WINDOW_TEXT_BOTTOM (w) - 1.
+ 	 If s_o_c_l is true, then we don't want to count a clipped
+ 	 line, so back up from the bottom by the height of the line
+ 	 containing point. */
+      if (scroll_on_clipped_lines)
+	pixpos -= Dynarr_atp (w->line_start_cache, cur_elt)->height;
+      else
+	pixpos -= 1;
+
+      if (cur_elt + new_line >= Dynarr_length (w->line_start_cache))
+	{
+	  /* Hit the bottom of the buffer. */
+	  int adjustment =
+	    (cur_elt + new_line) - Dynarr_length (w->line_start_cache) + 1;
+	  Lisp_Object window;
+	  int defheight;
+
+	  XSETWINDOW (window, w);
+	  default_face_height_and_width (window, &defheight, 0);
+
+	  cur_elt = Dynarr_length (w->line_start_cache) - 1;
+
+	  pixpos -= (adjustment * defheight);
+	  if (pixpos < WINDOW_TEXT_TOP (w))
+	    pixpos = WINDOW_TEXT_TOP (w);
+	}
+      else
+	cur_elt = cur_elt + new_line;
+
+      search_point = Dynarr_atp (w->line_start_cache, cur_elt)->start;
+
+      retval = start_with_line_at_pixpos (w, search_point, pixpos);
+      w->line_cache_validation_override--;
+      return retval;
+    }
+}
+
+/* This is used to speed up vertical scrolling by caching the known
+   buffer starting positions for display lines.  This allows the
+   scrolling routines to avoid costly calls to regenerate_window.  If
+   NO_REGEN is true then it will only add the values in the DESIRED
+   display structs which are in the given range.
+
+   Note also that the FROM/TO values are minimums.  It is possible
+   that this function will actually add information outside of the
+   lines containing those positions.  This can't hurt but it could
+   possibly help.
+
+   #### We currently force the cache to have only 1 contiguous region.
+   It might help to make the cache a dynarr of caches so that we can
+   cover more areas.  This might, however, turn out to be a lot of
+   overhead for too little gain. */
+
+static void
+update_line_start_cache (struct window *w, Bufpos from, Bufpos to,
+			 Bufpos point, int no_regen)
+{
+  struct buffer *b = XBUFFER (w->buffer);
+  line_start_cache_dynarr *cache = w->line_start_cache;
+  Bufpos low_bound, high_bound;
+
+  validate_line_start_cache (w);
+  w->line_cache_validation_override++;
+  updating_line_start_cache = 1;
+
+  if (from < BUF_BEGV (b))
+    from = BUF_BEGV (b);
+  if (to > BUF_ZV (b))
+    to = BUF_ZV (b);
+
+  if (from > to)
+    {
+      updating_line_start_cache = 0;
+      w->line_cache_validation_override--;
+      return;
+    }
+
+  if (Dynarr_length (cache))
+    {
+      low_bound = line_start_cache_start (w);
+      high_bound = line_start_cache_end (w);
+
+      /* Check to see if the desired range is already in the cache. */
+      if (from >= low_bound && to <= high_bound)
+	{
+	  updating_line_start_cache = 0;
+	  w->line_cache_validation_override--;
+	  return;
+	}
+
+      /* Check to make sure that the desired range is adjacent to the
+	 current cache.  If not, invalidate the cache. */
+      if (to < low_bound || from > high_bound)
+	{
+	  Dynarr_reset (cache);
+	  low_bound = high_bound = -1;
+	}
+    }
+  else
+    {
+      low_bound = high_bound = -1;
+    }
+
+  w->line_cache_last_updated = make_int (BUF_MODIFF (b));
+
+  /* This could be integrated into the next two sections, but it is easier
+     to follow what's going on by having it separate. */
+  if (no_regen)
+    {
+      Bufpos start, end;
+
+      update_internal_cache_list (w, DESIRED_DISP);
+      if (!Dynarr_length (internal_cache))
+	{
+	  updating_line_start_cache = 0;
+	  w->line_cache_validation_override--;
+	  return;
+	}
+
+      start = Dynarr_atp (internal_cache, 0)->start;
+      end =
+	Dynarr_atp (internal_cache, Dynarr_length (internal_cache) - 1)->end;
+
+      /* We aren't allowed to generate additional information to fill in
+         gaps, so if the DESIRED structs don't overlap the cache, reset the
+         cache. */
+      if (Dynarr_length (cache))
+	{
+	  if (end < low_bound || start > high_bound)
+	    Dynarr_reset (cache);
+
+	  /* #### What should really happen if what we are doing is
+             extending a line (the last line)? */
+	  if (Dynarr_length (cache) == 1
+	      && Dynarr_length (internal_cache) == 1)
+	    Dynarr_reset (cache);
+	}
+
+      if (!Dynarr_length (cache))
+	{
+	  Dynarr_add_many (cache, Dynarr_atp (internal_cache, 0),
+			   Dynarr_length (internal_cache));
+	  updating_line_start_cache = 0;
+	  w->line_cache_validation_override--;
+	  return;
+	}
+
+      /* An extra check just in case the calling function didn't pass in
+         the bounds of the DESIRED structs in the first place. */
+      if (start >= low_bound && end <= high_bound)
+	{
+	  updating_line_start_cache = 0;
+	  w->line_cache_validation_override--;
+	  return;
+	}
+
+      /* At this point we know that the internal cache partially overlaps
+         the main cache. */
+      if (start < low_bound)
+	{
+	  int ic_elt = Dynarr_length (internal_cache) - 1;
+	  while (ic_elt >= 0)
+	    {
+	      if (Dynarr_atp (internal_cache, ic_elt)->start < low_bound)
+		break;
+	      else
+		ic_elt--;
+	    }
+
+	  if (!(ic_elt >= 0))
+	    {
+	      Dynarr_reset (cache);
+	      Dynarr_add_many (cache, Dynarr_atp (internal_cache, 0),
+			       Dynarr_length (internal_cache));
+	      updating_line_start_cache = 0;
+	      w->line_cache_validation_override--;
+	      return;
+	    }
+
+	  Dynarr_insert_many_at_start (cache, Dynarr_atp (internal_cache, 0),
+			      ic_elt + 1);
+	}
+
+      if (end > high_bound)
+	{
+	  int ic_elt = 0;
+
+	  while (ic_elt < Dynarr_length (internal_cache))
+	    {
+	      if (Dynarr_atp (internal_cache, ic_elt)->start > high_bound)
+		break;
+	      else
+		ic_elt++;
+	    }
+
+	  if (!(ic_elt < Dynarr_length (internal_cache)))
+	    {
+	      Dynarr_reset (cache);
+	      Dynarr_add_many (cache, Dynarr_atp (internal_cache, 0),
+			       Dynarr_length (internal_cache));
+	      updating_line_start_cache = 0;
+	      w->line_cache_validation_override--;
+	      return;
+	    }
+
+	  Dynarr_add_many (cache, Dynarr_atp (internal_cache, ic_elt),
+			   Dynarr_length (internal_cache) - ic_elt);
+	}
+
+      updating_line_start_cache = 0;
+      w->line_cache_validation_override--;
+      return;
+    }
+
+  if (!Dynarr_length (cache) || from < low_bound)
+    {
+      Bufpos startp = find_next_newline_no_quit (b, from, -1);
+      int marker = 0;
+      int old_lb = low_bound;
+
+      while (startp < old_lb || low_bound == -1)
+	{
+	  int ic_elt;
+          Bufpos new_startp;
+
+	  regenerate_window (w, startp, point, CMOTION_DISP);
+	  update_internal_cache_list (w, CMOTION_DISP);
+
+	  /* If this assert is triggered then regenerate_window failed
+             to layout a single line.  That is not supposed to be
+             possible because we impose a minimum height on the buffer
+             and override vertical clip when we are in here. */
+	  /* #### Ah, but it is because the window may temporarily
+             exist but not have any lines at all if the minibuffer is
+             real big.  Look into that situation better. */
+	  if (!Dynarr_length (internal_cache))
+	    {
+	      if (old_lb == -1 && low_bound == -1)
+		{
+		  updating_line_start_cache = 0;
+		  w->line_cache_validation_override--;
+		  return;
+		}
+
+	      assert (Dynarr_length (internal_cache));
+	    }
+	  assert (startp == Dynarr_atp (internal_cache, 0)->start);
+
+	  ic_elt = Dynarr_length (internal_cache) - 1;
+	  if (low_bound != -1)
+	    {
+	      while (ic_elt >= 0)
+		{
+		  if (Dynarr_atp (internal_cache, ic_elt)->start < old_lb)
+		    break;
+		  else
+		    ic_elt--;
+		}
+	    }
+	  assert (ic_elt >= 0);
+
+	  new_startp = Dynarr_atp (internal_cache, ic_elt)->end + 1;
+
+          /*
+           * Handle invisible text properly:
+           * If the last line we're inserting has the same end as the
+           * line before which it will be added, merge the two lines.
+           */
+          if (Dynarr_length (cache)  &&
+              Dynarr_atp (internal_cache, ic_elt)->end ==
+              Dynarr_atp (cache, marker)->end)
+            {
+              Dynarr_atp (cache, marker)->start
+                = Dynarr_atp (internal_cache, ic_elt)->start;
+              Dynarr_atp (cache, marker)->height
+                = Dynarr_atp (internal_cache, ic_elt)->height;
+              ic_elt--;
+            }
+
+          if (ic_elt >= 0)       /* we still have lines to add.. */
+            {
+              Dynarr_insert_many (cache, Dynarr_atp (internal_cache, 0),
+                                  ic_elt + 1, marker);
+              marker += (ic_elt + 1);
+            }
+
+	  if (startp < low_bound || low_bound == -1)
+	    low_bound = startp;
+	  startp = new_startp;
+	  if (startp > BUF_ZV (b))
+	    {
+	      updating_line_start_cache = 0;
+	      w->line_cache_validation_override--;
+	      return;
+	    }
+	}
+    }
+
+  assert (Dynarr_length (cache));
+  assert (from >= low_bound);
+
+  /* Readjust the high_bound to account for any changes made while
+     correcting the low_bound. */
+  high_bound = Dynarr_atp (cache, Dynarr_length (cache) - 1)->end;
+
+  if (to > high_bound)
+    {
+      Bufpos startp = Dynarr_atp (cache, Dynarr_length (cache) - 1)->end + 1;
+
+      do
+	{
+	  regenerate_window (w, startp, point, CMOTION_DISP);
+	  update_internal_cache_list (w, CMOTION_DISP);
+
+	  /* See comment above about regenerate_window failing. */
+	  assert (Dynarr_length (internal_cache));
+
+	  Dynarr_add_many (cache, Dynarr_atp (internal_cache, 0),
+			   Dynarr_length (internal_cache));
+	  high_bound = Dynarr_atp (cache, Dynarr_length (cache) - 1)->end;
+	  startp = high_bound + 1;
+	}
+      while (to > high_bound);
+    }
+
+  updating_line_start_cache = 0;
+  w->line_cache_validation_override--;
+  assert (to <= high_bound);
+}
+
+
+/* Given x and y coordinates in characters, relative to a window,
+   return the pixel location corresponding to those coordinates.  The
+   pixel location returned is the center of the given character
+   position.  The pixel values are generated relative to the window,
+   not the frame.
+
+   The modeline is considered to be part of the window. */
+
+void
+glyph_to_pixel_translation (struct window *w, int char_x, int char_y,
+			    int *pix_x, int *pix_y)
+{
+  display_line_dynarr *dla = window_display_lines (w, CURRENT_DISP);
+  int num_disp_lines, modeline;
+  Lisp_Object window;
+  int defheight, defwidth;
+
+  XSETWINDOW (window, w);
+  default_face_height_and_width (window, &defheight, &defwidth);
+
+  /* If we get a bogus value indicating somewhere above or to the left of
+     the window, use the first window line or character position
+     instead. */
+  if (char_y < 0)
+    char_y = 0;
+  if (char_x < 0)
+    char_x = 0;
+
+  num_disp_lines = Dynarr_length (dla);
+  modeline = 0;
+  if (num_disp_lines)
+    {
+      if (Dynarr_atp (dla, 0)->modeline)
+	{
+	  num_disp_lines--;
+	  modeline = 1;
+	}
+    }
+
+  /* First check if the y position intersects the display lines. */
+  if (char_y < num_disp_lines)
+    {
+      struct display_line *dl = Dynarr_atp (dla, char_y + modeline);
+      struct display_block *db = get_display_block_from_line (dl, TEXT);
+
+      *pix_y = (dl->ypos - dl->ascent +
+		((unsigned int) (dl->ascent + dl->descent - dl->clip) >> 1));
+
+      if (char_x < Dynarr_length (db->runes))
+	{
+	  struct rune *rb = Dynarr_atp (db->runes, char_x);
+
+	  *pix_x = rb->xpos + (rb->width >> 1);
+	}
+      else
+	{
+	  int last_rune = Dynarr_length (db->runes) - 1;
+	  struct rune *rb = Dynarr_atp (db->runes, last_rune);
+
+	  char_x -= last_rune;
+
+	  *pix_x = rb->xpos + rb->width;
+	  *pix_x += ((char_x - 1) * defwidth);
+	  *pix_x += (defwidth >> 1);
+	}
+    }
+  else
+    {
+      /* It didn't intersect, so extrapolate.  #### For now, we include the
+	 modeline in this since we don't have true character positions in
+	 it. */
+
+      if (!Dynarr_length (w->face_cachels))
+	reset_face_cachels (w);
+
+      char_y -= num_disp_lines;
+
+      if (Dynarr_length (dla))
+	{
+	  struct display_line *dl = Dynarr_atp (dla, Dynarr_length (dla) - 1);
+	  *pix_y = dl->ypos + dl->descent - dl->clip;
+	}
+      else
+	*pix_y = WINDOW_TEXT_TOP (w);
+
+      *pix_y += (char_y * defheight);
+      *pix_y += (defheight >> 1);
+
+      *pix_x = WINDOW_TEXT_LEFT (w);
+      /* Don't adjust by one because this is still the unadjusted value. */
+      *pix_x += (char_x * defwidth);
+      *pix_x += (defwidth >> 1);
+    }
+
+  if (*pix_x > w->pixel_left + w->pixel_width)
+      *pix_x = w->pixel_left + w->pixel_width;
+  if (*pix_y > w->pixel_top + w->pixel_height)
+      *pix_y = w->pixel_top + w->pixel_height;
+
+  *pix_x -= w->pixel_left;
+  *pix_y -= w->pixel_top;
+}
+
+/* Given a display line and a position, determine if there is a glyph
+   there and return information about it if there is. */
+
+static void
+get_position_object (struct display_line *dl, Lisp_Object *obj1,
+		     Lisp_Object *obj2, int x_coord, int *low_x_coord,
+		     int *high_x_coord)
+{
+  struct display_block *db;
+  int elt;
+  int block =
+    get_next_display_block (dl->bounds, dl->display_blocks, x_coord, 0);
+
+  /* We use get_next_display_block to get the actual display block
+     that would be displayed at x_coord. */
+
+  if (block == NO_BLOCK)
+    return;
+  else
+    db = Dynarr_atp (dl->display_blocks, block);
+
+  for (elt = 0; elt < Dynarr_length (db->runes); elt++)
+    {
+      struct rune *rb = Dynarr_atp (db->runes, elt);
+
+      if (rb->xpos <= x_coord && x_coord < (rb->xpos + rb->width))
+	{
+	  if (rb->type == RUNE_DGLYPH)
+	    {
+	      *obj1 = rb->object.dglyph.glyph;
+	      *obj2 = rb->object.dglyph.extent;
+	    }
+	  else
+	    {
+	      *obj1 = Qnil;
+	      *obj2 = Qnil;
+	    }
+
+	  if (low_x_coord)
+	    *low_x_coord = rb->xpos;
+	  if (high_x_coord)
+	    *high_x_coord = rb->xpos + rb->width;
+
+	  return;
+	}
+    }
+}
+
+#define UPDATE_CACHE_RETURN						\
+  do {									\
+    d->pixel_to_glyph_cache.valid = 1;					\
+    d->pixel_to_glyph_cache.low_x_coord = low_x_coord;			\
+    d->pixel_to_glyph_cache.high_x_coord = high_x_coord;		\
+    d->pixel_to_glyph_cache.low_y_coord = low_y_coord;			\
+    d->pixel_to_glyph_cache.high_y_coord = high_y_coord;		\
+    d->pixel_to_glyph_cache.frame = f;					\
+    d->pixel_to_glyph_cache.col = *col;					\
+    d->pixel_to_glyph_cache.row = *row;					\
+    d->pixel_to_glyph_cache.obj_x = *obj_x;				\
+    d->pixel_to_glyph_cache.obj_y = *obj_y;				\
+    d->pixel_to_glyph_cache.w = *w;					\
+    d->pixel_to_glyph_cache.bufpos = *bufpos;				\
+    d->pixel_to_glyph_cache.closest = *closest;				\
+    d->pixel_to_glyph_cache.modeline_closest = *modeline_closest;	\
+    d->pixel_to_glyph_cache.obj1 = *obj1;				\
+    d->pixel_to_glyph_cache.obj2 = *obj2;				\
+    d->pixel_to_glyph_cache.retval = position;				\
+    RETURN_SANS_WARNINGS position;					\
+  } while (0)
+
+/* Given x and y coordinates in pixels relative to a frame, return
+   information about what is located under those coordinates.
+
+   The return value will be one of:
+
+     OVER_TOOLBAR:	over one of the 4 frame toolbars
+     OVER_MODELINE:	over a modeline
+     OVER_BORDER:	over an internal border
+     OVER_NOTHING:	over the text area, but not over text
+     OVER_OUTSIDE:	outside of the frame border
+     OVER_TEXT:		over text in the text area
+
+   OBJ1 is one of
+
+     -- a toolbar button
+     -- a glyph
+     -- nil if the coordinates are not over a glyph or a toolbar button.
+
+   OBJ2 is one of
+
+     -- an extent, if the coordinates are over a glyph in the text area
+     -- nil otherwise.
+
+   If the coordinates are over a glyph, OBJ_X and OBJ_Y give the
+   equivalent coordinates relative to the upper-left corner of the glyph.
+
+   If the coordinates are over a character, OBJ_X and OBJ_Y give the
+   equivalent coordinates relative to the upper-left corner of the character.
+
+   Otherwise, OBJ_X and OBJ_Y are undefined.
+   */
+
+int
+pixel_to_glyph_translation (struct frame *f, int x_coord, int y_coord,
+			    int *col, int *row, int *obj_x, int *obj_y,
+			    struct window **w, Bufpos *bufpos,
+			    Bufpos *closest, Charcount *modeline_closest,
+			    Lisp_Object *obj1, Lisp_Object *obj2)
+{
+  struct device *d;
+  struct pixel_to_glyph_translation_cache *cache;
+  Lisp_Object window;
+  int frm_left, frm_right, frm_top, frm_bottom;
+  int low_x_coord, high_x_coord, low_y_coord, high_y_coord;
+  int position = OVER_NOTHING;
+  int device_check_failed = 0;
+  display_line_dynarr *dla;
+
+  /* This is a safety valve in case this got called with a frame in
+     the middle of being deleted. */
+  if (!DEVICEP (f->device) || !DEVICE_LIVE_P (XDEVICE (f->device)))
+    {
+      device_check_failed = 1;
+      d = NULL, cache = NULL; /* Warning suppression */
+    }
+  else
+    {
+      d = XDEVICE (f->device);
+      cache = &d->pixel_to_glyph_cache;
+    }
+
+  if (!device_check_failed
+      && cache->valid
+      && cache->frame == f
+      && cache->low_x_coord <= x_coord
+      && cache->high_x_coord > x_coord
+      && cache->low_y_coord <= y_coord
+      && cache->high_y_coord > y_coord)
+    {
+      *col = cache->col;
+      *row = cache->row;
+      *obj_x = cache->obj_x;
+      *obj_y = cache->obj_y;
+      *w = cache->w;
+      *bufpos = cache->bufpos;
+      *closest = cache->closest;
+      *modeline_closest = cache->modeline_closest;
+      *obj1 = cache->obj1;
+      *obj2 = cache->obj2;
+
+      return cache->retval;
+    }
+  else
+    {
+      *col = 0;
+      *row = 0;
+      *obj_x = 0;
+      *obj_y = 0;
+      *w = 0;
+      *bufpos = 0;
+      *closest = 0;
+      *modeline_closest = -1;
+      *obj1 = Qnil;
+      *obj2 = Qnil;
+
+      low_x_coord = x_coord;
+      high_x_coord = x_coord + 1;
+      low_y_coord = y_coord;
+      high_y_coord = y_coord + 1;
+    }
+
+  if (device_check_failed)
+    return OVER_NOTHING;
+
+  frm_left = FRAME_LEFT_BORDER_END (f);
+  frm_right = FRAME_RIGHT_BORDER_START (f);
+  frm_top = FRAME_TOP_BORDER_END (f);
+  frm_bottom = FRAME_BOTTOM_BORDER_START (f);
+
+  /* Check if the mouse is outside of the text area actually used by
+     redisplay. */
+  if (y_coord < frm_top)
+    {
+      if (y_coord >= FRAME_TOP_BORDER_START (f))
+	{
+	  low_y_coord = FRAME_TOP_BORDER_START (f);
+	  high_y_coord = frm_top;
+	  position = OVER_BORDER;
+	}
+      else if (y_coord >= 0)
+	{
+	  low_y_coord = 0;
+	  high_y_coord = FRAME_TOP_BORDER_START (f);
+	  position = OVER_TOOLBAR;
+	}
+      else
+	{
+	  low_y_coord = y_coord;
+	  high_y_coord = 0;
+	  position = OVER_OUTSIDE;
+	}
+    }
+  else if (y_coord >= frm_bottom)
+    {
+      if (y_coord < FRAME_BOTTOM_BORDER_END (f))
+	{
+	  low_y_coord = frm_bottom;
+	  high_y_coord = FRAME_BOTTOM_BORDER_END (f);
+	  position = OVER_BORDER;
+	}
+      else if (y_coord < FRAME_PIXHEIGHT (f))
+	{
+	  low_y_coord = FRAME_BOTTOM_BORDER_END (f);
+	  high_y_coord = FRAME_PIXHEIGHT (f);
+	  position = OVER_TOOLBAR;
+	}
+      else
+	{
+	  low_y_coord = FRAME_PIXHEIGHT (f);
+	  high_y_coord = y_coord;
+	  position = OVER_OUTSIDE;
+	}
+    }
+
+  if (position != OVER_TOOLBAR && position != OVER_BORDER)
+    {
+      if (x_coord < frm_left)
+	{
+	  if (x_coord >= FRAME_LEFT_BORDER_START (f))
+	    {
+	      low_x_coord = FRAME_LEFT_BORDER_START (f);
+	      high_x_coord = frm_left;
+	      position = OVER_BORDER;
+	    }
+	  else if (x_coord >= 0)
+	    {
+	      low_x_coord = 0;
+	      high_x_coord = FRAME_LEFT_BORDER_START (f);
+	      position = OVER_TOOLBAR;
+	    }
+	  else
+	    {
+	      low_x_coord = x_coord;
+	      high_x_coord = 0;
+	      position = OVER_OUTSIDE;
+	    }
+	}
+      else if (x_coord >= frm_right)
+	{
+	  if (x_coord < FRAME_RIGHT_BORDER_END (f))
+	    {
+	      low_x_coord = frm_right;
+	      high_x_coord = FRAME_RIGHT_BORDER_END (f);
+	      position = OVER_BORDER;
+	    }
+	  else if (x_coord < FRAME_PIXWIDTH (f))
+	    {
+	      low_x_coord = FRAME_RIGHT_BORDER_END (f);
+	      high_x_coord = FRAME_PIXWIDTH (f);
+	      position = OVER_TOOLBAR;
+	    }
+	  else
+	    {
+	      low_x_coord = FRAME_PIXWIDTH (f);
+	      high_x_coord = x_coord;
+	      position = OVER_OUTSIDE;
+	    }
+	}
+    }
+
+#ifdef HAVE_TOOLBARS
+  if (position == OVER_TOOLBAR)
+    {
+      *obj1 = toolbar_button_at_pixpos (f, x_coord, y_coord);
+      *obj2 = Qnil;
+      *w = 0;
+      UPDATE_CACHE_RETURN;
+    }
+#endif /* HAVE_TOOLBARS */
+
+  /* We still have to return the window the pointer is next to and its
+     relative y position even if it is outside the x boundary. */
+  if (x_coord < frm_left)
+    x_coord = frm_left;
+  else if (x_coord > frm_right)
+    x_coord = frm_right;
+
+  /* Same in reverse. */
+  if (y_coord < frm_top)
+    y_coord = frm_top;
+  else if (y_coord > frm_bottom)
+    y_coord = frm_bottom;
+
+  /* Find what window the given coordinates are actually in. */
+  window = f->root_window;
+  *w = find_window_by_pixel_pos (x_coord, y_coord, window);
+
+  /* If we didn't find a window, we're done. */
+  if (!*w)
+    {
+      UPDATE_CACHE_RETURN;
+    }
+  else if (position != OVER_NOTHING)
+    {
+      *closest = 0;
+      *modeline_closest = -1;
+
+      if (high_y_coord <= frm_top || high_y_coord >= frm_bottom)
+	{
+	  *w = 0;
+	  UPDATE_CACHE_RETURN;
+	}
+    }
+
+  /* Check if the window is a minibuffer but isn't active. */
+  if (MINI_WINDOW_P (*w) && !minibuf_level)
+    {
+      /* Must reset the window value since some callers will ignore
+         the return value if it is set. */
+      *w = 0;
+      UPDATE_CACHE_RETURN;
+    }
+
+  /* See if the point is over window vertical divider */
+  if (window_needs_vertical_divider (*w))
+    {
+      int div_x_high = WINDOW_RIGHT (*w);
+      int div_x_low  = div_x_high - window_divider_width (*w);
+      int div_y_high = WINDOW_BOTTOM (*w);
+      int div_y_low  = WINDOW_TOP (*w);
+
+      if (div_x_low < x_coord && x_coord <= div_x_high &&
+	  div_y_low < y_coord && y_coord <= div_y_high)
+	{
+	  low_x_coord = div_x_low;
+	  high_x_coord = div_x_high;
+	  low_y_coord = div_y_low;
+	  high_y_coord = div_y_high;
+	  position = OVER_V_DIVIDER;
+	  UPDATE_CACHE_RETURN;
+	}
+    }
+
+  dla = window_display_lines (*w, CURRENT_DISP);
+
+  for (*row = 0; *row < Dynarr_length (dla); (*row)++)
+    {
+      int really_over_nothing = 0;
+      struct display_line *dl = Dynarr_atp (dla, *row);
+
+      if ((int) (dl->ypos - dl->ascent) <= y_coord
+	  && y_coord <= (int) (dl->ypos + dl->descent))
+	{
+	  int check_margin_glyphs = 0;
+	  struct display_block *db = get_display_block_from_line (dl, TEXT);
+	  struct rune *rb = 0;
+
+	  if (x_coord < dl->bounds.left_white
+	      || x_coord >= dl->bounds.right_white)
+	    check_margin_glyphs = 1;
+
+	  low_y_coord = dl->ypos - dl->ascent;
+	  high_y_coord = dl->ypos + dl->descent + 1;
+
+	  if (position == OVER_BORDER
+	      || position == OVER_OUTSIDE
+	      || check_margin_glyphs)
+	    {
+	      int x_check, left_bound;
+
+	      if (check_margin_glyphs)
+		{
+		  x_check = x_coord;
+		  left_bound = dl->bounds.left_white;
+		}
+	      else
+		{
+		  x_check = high_x_coord;
+		  left_bound = frm_left;
+		}
+
+	      if (Dynarr_length (db->runes))
+		{
+		  if (x_check <= left_bound)
+		    {
+		      if (dl->modeline)
+			*modeline_closest = Dynarr_atp (db->runes, 0)->bufpos;
+		      else
+			*closest = Dynarr_atp (db->runes, 0)->bufpos;
+		    }
+		  else
+		    {
+		      if (dl->modeline)
+			*modeline_closest =
+			  Dynarr_atp (db->runes,
+				      Dynarr_length (db->runes) - 1)->bufpos;
+		      else
+			*closest =
+			  Dynarr_atp (db->runes,
+				      Dynarr_length (db->runes) - 1)->bufpos;
+		    }
+
+		  if (dl->modeline)
+		    *modeline_closest += dl->offset;
+		  else
+		    *closest += dl->offset;
+		}
+	      else
+		{
+		  /* #### What should be here. */
+		  if (dl->modeline)
+		    *modeline_closest = 0;
+		  else
+		    *closest = 0;
+		}
+
+	      if (check_margin_glyphs)
+		{
+		  if (x_coord < dl->bounds.left_in
+		      || x_coord >= dl->bounds.right_in)
+		    {
+		      /* If we are over the outside margins then we
+                         know the loop over the text block isn't going
+                         to accomplish anything.  So we go ahead and
+                         set what information we can right here and
+                         return. */
+		      (*row)--;
+		      *obj_y = y_coord - (dl->ypos - dl->ascent);
+		      get_position_object (dl, obj1, obj2, x_coord,
+					   &low_x_coord, &high_x_coord);
+
+		      UPDATE_CACHE_RETURN;
+		    }
+		}
+	      else
+		UPDATE_CACHE_RETURN;
+	    }
+
+	  for (*col = 0; *col <= Dynarr_length (db->runes); (*col)++)
+	    {
+	      int past_end = (*col == Dynarr_length (db->runes));
+
+	      if (!past_end)
+		rb = Dynarr_atp (db->runes, *col);
+
+	      if (past_end ||
+		  (rb->xpos <= x_coord && x_coord < rb->xpos + rb->width))
+		{
+		  if (past_end)
+		    {
+		      (*col)--;
+		      rb = Dynarr_atp (db->runes, *col);
+		    }
+
+		  *bufpos = rb->bufpos + dl->offset;
+		  low_x_coord = rb->xpos;
+		  high_x_coord = rb->xpos + rb->width;
+
+		  if (rb->type == RUNE_DGLYPH)
+		    {
+		      int elt = *col + 1;
+
+		      /* Find the first character after the glyph. */
+		      while (elt < Dynarr_length (db->runes))
+			{
+			  if (Dynarr_atp (db->runes, elt)->type != RUNE_DGLYPH)
+			    {
+			      if (dl->modeline)
+				*modeline_closest =
+				  (Dynarr_atp (db->runes, elt)->bufpos +
+				   dl->offset);
+			      else
+				*closest =
+				  (Dynarr_atp (db->runes, elt)->bufpos +
+				   dl->offset);
+			      break;
+			    }
+
+			  elt++;
+			}
+
+		      /* In this case we failed to find a non-glyph
+                         character so we return the last position
+                         displayed on the line. */
+		      if (elt == Dynarr_length (db->runes))
+			{
+			  if (dl->modeline)
+			    *modeline_closest = dl->end_bufpos + dl->offset;
+			  else
+			    *closest = dl->end_bufpos + dl->offset;
+			  really_over_nothing = 1;
+			}
+		    }
+		  else
+		    {
+		      if (dl->modeline)
+			*modeline_closest = rb->bufpos + dl->offset;
+		      else
+			*closest = rb->bufpos + dl->offset;
+		    }
+
+		  if (dl->modeline)
+		    {
+		      *row = window_displayed_height (*w);
+
+		      if (position == OVER_NOTHING)
+			position = OVER_MODELINE;
+
+		      if (rb->type == RUNE_DGLYPH)
+			{
+			  *obj1 = rb->object.dglyph.glyph;
+			  *obj2 = rb->object.dglyph.extent;
+			}
+		      else if (rb->type == RUNE_CHAR)
+			{
+			  *obj1 = Qnil;
+			  *obj2 = Qnil;
+			}
+		      else
+			{
+			  *obj1 = Qnil;
+			  *obj2 = Qnil;
+			}
+
+		      UPDATE_CACHE_RETURN;
+		    }
+		  else if (past_end
+			   || (rb->type == RUNE_CHAR
+			       && rb->object.chr.ch == '\n'))
+		    {
+		      (*row)--;
+		      /* At this point we may have glyphs in the right
+                         inside margin. */
+		      if (check_margin_glyphs)
+			get_position_object (dl, obj1, obj2, x_coord,
+					     &low_x_coord, &high_x_coord);
+		      UPDATE_CACHE_RETURN;
+		    }
+		  else
+		    {
+		      (*row)--;
+		      if (rb->type == RUNE_DGLYPH)
+			{
+			  *obj1 = rb->object.dglyph.glyph;
+			  *obj2 = rb->object.dglyph.extent;
+			}
+		      else if (rb->type == RUNE_CHAR)
+			{
+			  *obj1 = Qnil;
+			  *obj2 = Qnil;
+			}
+		      else
+			{
+			  *obj1 = Qnil;
+			  *obj2 = Qnil;
+			}
+
+		      *obj_x = x_coord - rb->xpos;
+		      *obj_y = y_coord - (dl->ypos - dl->ascent);
+
+		      /* At this point we may have glyphs in the left
+                         inside margin. */
+		      if (check_margin_glyphs)
+			get_position_object (dl, obj1, obj2, x_coord, 0, 0);
+
+		      if (position == OVER_NOTHING && !really_over_nothing)
+			position = OVER_TEXT;
+
+		      UPDATE_CACHE_RETURN;
+		    }
+		}
+	    }
+	}
+    }
+
+  *row = Dynarr_length (dla) - 1;
+  if (FRAME_WIN_P (f))
+    {
+      int bot_elt = Dynarr_length (dla) - 1;
+
+      if (bot_elt >= 0)
+	{
+	  struct display_line *dl = Dynarr_atp (dla, bot_elt);
+	  int adj_area = y_coord - (dl->ypos + dl->descent);
+	  Lisp_Object lwin;
+	  int defheight;
+
+	  XSETWINDOW (lwin, *w);
+	  default_face_height_and_width (lwin, 0, &defheight);
+
+	  *row += (adj_area / defheight);
+	}
+    }
+
+  /* #### This should be checked out some more to determine what
+     should really be going on. */
+  if (!MARKERP ((*w)->start[CURRENT_DISP]))
+    *closest = 0;
+  else
+    *closest = end_of_last_line (*w,
+				 marker_position ((*w)->start[CURRENT_DISP]));
+  *col = 0;
+  UPDATE_CACHE_RETURN;
+}
+#undef UPDATE_CACHE_RETURN
+
+
+/***************************************************************************/
+/*									   */
+/*                             Lisp functions                              */
+/*									   */
+/***************************************************************************/
+
+DEFUN ("redisplay-echo-area", Fredisplay_echo_area, 0, 0, 0, /*
+Ensure that all minibuffers are correctly showing the echo area.
+*/
+       ())
+{
+  Lisp_Object devcons, concons;
+
+  DEVICE_LOOP_NO_BREAK (devcons, concons)
+    {
+      struct device *d = XDEVICE (XCAR (devcons));
+      Lisp_Object frmcons;
+
+      DEVICE_FRAME_LOOP (frmcons, d)
+	{
+	  struct frame *f = XFRAME (XCAR (frmcons));
+
+	  if (FRAME_REPAINT_P (f) && FRAME_HAS_MINIBUF_P (f))
+	    {
+	      Lisp_Object window = FRAME_MINIBUF_WINDOW (f);
+	      /*
+	       * If the frame size has changed, there may be random
+	       * chud on the screen left from previous messages
+	       * because redisplay_frame hasn't been called yet.
+	       * Clear the screen to get rid of the potential mess.
+	       */
+	      if (f->echo_area_garbaged)
+		{
+		  DEVMETH (d, clear_frame, (f));
+		  f->echo_area_garbaged = 0;
+		}
+	      redisplay_window (window, 0);
+	      call_redisplay_end_triggers (XWINDOW (window), 0);
+	    }
+	}
+
+      /* We now call the output_end routine for tty frames.  We delay
+	 doing so in order to avoid cursor flicker.  So much for 100%
+	 encapsulation. */
+      if (DEVICE_TTY_P (d))
+	DEVMETH (d, output_end, (d));
+    }
+
+  return Qnil;
+}
+
+static Lisp_Object
+restore_disable_preemption_value (Lisp_Object value)
+{
+  disable_preemption = XINT (value);
+  return Qnil;
+}
+
+DEFUN ("redraw-frame", Fredraw_frame, 0, 2, 0, /*
+Clear frame FRAME and output again what is supposed to appear on it.
+FRAME defaults to the selected frame if omitted.
+Normally, redisplay is preempted as normal if input arrives.  However,
+if optional second arg NO-PREEMPT is non-nil, redisplay will not stop for
+input and is guaranteed to proceed to completion.
+*/
+       (frame, no_preempt))
+{
+  struct frame *f = decode_frame (frame);
+  int count = specpdl_depth ();
+
+  if (!NILP (no_preempt))
+    {
+      record_unwind_protect (restore_disable_preemption_value,
+			     make_int (disable_preemption));
+      disable_preemption++;
+    }
+
+  f->clear = 1;
+  redisplay_frame (f, 1);
+
+  return unbind_to (count, Qnil);
+}
+
+DEFUN ("redisplay-frame", Fredisplay_frame, 0, 2, 0, /*
+Ensure that FRAME's contents are correctly displayed.
+This differs from `redraw-frame' in that it only redraws what needs to
+be updated, as opposed to unconditionally clearing and redrawing
+the frame.
+FRAME defaults to the selected frame if omitted.
+Normally, redisplay is preempted as normal if input arrives.  However,
+if optional second arg NO-PREEMPT is non-nil, redisplay will not stop for
+input and is guaranteed to proceed to completion.
+*/
+       (frame, no_preempt))
+{
+  struct frame *f = decode_frame (frame);
+  int count = specpdl_depth ();
+
+  if (!NILP (no_preempt))
+    {
+      record_unwind_protect (restore_disable_preemption_value,
+			     make_int (disable_preemption));
+      disable_preemption++;
+    }
+
+  redisplay_frame (f, 1);
+
+  return unbind_to (count, Qnil);
+}
+
+DEFUN ("redraw-device", Fredraw_device, 0, 2, 0, /*
+Clear device DEVICE and output again what is supposed to appear on it.
+DEVICE defaults to the selected device if omitted.
+Normally, redisplay is preempted as normal if input arrives.  However,
+if optional second arg NO-PREEMPT is non-nil, redisplay will not stop for
+input and is guaranteed to proceed to completion.
+*/
+     (device, no_preempt))
+{
+  struct device *d = decode_device (device);
+  Lisp_Object frmcons;
+  int count = specpdl_depth ();
+
+  if (!NILP (no_preempt))
+    {
+      record_unwind_protect (restore_disable_preemption_value,
+			     make_int (disable_preemption));
+      disable_preemption++;
+    }
+
+  DEVICE_FRAME_LOOP (frmcons, d)
+    {
+      XFRAME (XCAR (frmcons))->clear = 1;
+    }
+  redisplay_device (d);
+
+  return unbind_to (count, Qnil);
+}
+
+DEFUN ("redisplay-device", Fredisplay_device, 0, 2, 0, /*
+Ensure that DEVICE's contents are correctly displayed.
+This differs from `redraw-device' in that it only redraws what needs to
+be updated, as opposed to unconditionally clearing and redrawing
+the device.
+DEVICE defaults to the selected device if omitted.
+Normally, redisplay is preempted as normal if input arrives.  However,
+if optional second arg NO-PREEMPT is non-nil, redisplay will not stop for
+input and is guaranteed to proceed to completion.
+*/
+       (device, no_preempt))
+{
+  struct device *d = decode_device (device);
+  int count = specpdl_depth ();
+
+  if (!NILP (no_preempt))
+    {
+      record_unwind_protect (restore_disable_preemption_value,
+			     make_int (disable_preemption));
+      disable_preemption++;
+    }
+
+  redisplay_device (d);
+
+  return unbind_to (count, Qnil);
+}
+
+/* Big lie.  Big lie.  This will force all modelines to be updated
+   regardless if the all flag is set or not.  It remains in existence
+   solely for backwards compatibility. */
+DEFUN ("redraw-modeline", Fredraw_modeline, 0, 1, 0, /*
+Force the modeline of the current buffer to be redisplayed.
+With optional non-nil ALL, force redisplay of all modelines.
+*/
+       (all))
+{
+  MARK_MODELINE_CHANGED;
+  return Qnil;
+}
+
+DEFUN ("force-cursor-redisplay", Fforce_cursor_redisplay, 0, 1, 0, /*
+Force an immediate update of the cursor on FRAME.
+FRAME defaults to the selected frame if omitted.
+*/
+  (frame))
+{
+  redisplay_redraw_cursor (decode_frame (frame), 1);
+  return Qnil;
+}
+
+
+/***************************************************************************/
+/*									   */
+/*                     Lisp-variable change triggers                       */
+/*									   */
+/***************************************************************************/
+
+static void
+margin_width_changed_in_frame (Lisp_Object specifier, struct frame *f,
+			       Lisp_Object oldval)
+{
+  /* Nothing to be done? */
+}
+
+int
+redisplay_variable_changed (Lisp_Object sym, Lisp_Object *val,
+			    Lisp_Object in_object, int flags)
+{
+  /* #### clip_changed should really be renamed something like
+     global_redisplay_change. */
+  MARK_CLIP_CHANGED;
+  return 0;
+}
+
+/* This is called if the built-in glyphs have their properties
+   changed. */
+void
+redisplay_glyph_changed (Lisp_Object glyph, Lisp_Object property,
+			 Lisp_Object locale)
+{
+  if (WINDOWP (locale))
+    {
+      MARK_FRAME_GLYPHS_CHANGED (XFRAME (WINDOW_FRAME (XWINDOW (locale))));
+    }
+  else if (FRAMEP (locale))
+    {
+      MARK_FRAME_GLYPHS_CHANGED (XFRAME (locale));
+    }
+  else if (DEVICEP (locale))
+    {
+      Lisp_Object frmcons;
+      DEVICE_FRAME_LOOP (frmcons, XDEVICE (locale))
+	MARK_FRAME_GLYPHS_CHANGED (XFRAME (XCAR (frmcons)));
+    }
+  else if (CONSOLEP (locale))
+    {
+      Lisp_Object frmcons, devcons;
+      CONSOLE_FRAME_LOOP_NO_BREAK (frmcons, devcons, XCONSOLE (locale))
+	MARK_FRAME_GLYPHS_CHANGED (XFRAME (XCAR (frmcons)));
+    }
+  else /* global or buffer */
+    {
+      Lisp_Object frmcons, devcons, concons;
+      FRAME_LOOP_NO_BREAK (frmcons, devcons, concons)
+	MARK_FRAME_GLYPHS_CHANGED (XFRAME (XCAR (frmcons)));
+    }
+}
+
+static void
+text_cursor_visible_p_changed (Lisp_Object specifier, struct window *w,
+			       Lisp_Object oldval)
+{
+  if (XFRAME (w->frame)->init_finished)
+    Fforce_cursor_redisplay (w->frame);
+}
+
+#ifdef MEMORY_USAGE_STATS
+
+
+/***************************************************************************/
+/*									   */
+/*                        memory usage computation                         */
+/*									   */
+/***************************************************************************/
+
+static int
+compute_rune_dynarr_usage (rune_dynarr *dyn, struct overhead_stats *ovstats)
+{
+  return dyn ? Dynarr_memory_usage (dyn, ovstats) : 0;
+}
+
+static int
+compute_display_block_dynarr_usage (display_block_dynarr *dyn,
+				    struct overhead_stats *ovstats)
+{
+  int total, i;
+
+  if (!dyn)
+    return 0;
+
+  total = Dynarr_memory_usage (dyn, ovstats);
+  for (i = 0; i < Dynarr_largest (dyn); i++)
+    total += compute_rune_dynarr_usage (Dynarr_at (dyn, i).runes, ovstats);
+
+  return total;
+}
+
+static int
+compute_glyph_block_dynarr_usage (glyph_block_dynarr *dyn,
+				  struct overhead_stats *ovstats)
+{
+  return dyn ? Dynarr_memory_usage (dyn, ovstats) : 0;
+}
+
+int
+compute_display_line_dynarr_usage (display_line_dynarr *dyn,
+				   struct overhead_stats *ovstats)
+{
+  int total, i;
+
+  if (!dyn)
+    return 0;
+
+  total = Dynarr_memory_usage (dyn, ovstats);
+  for (i = 0; i < Dynarr_largest (dyn); i++)
+    {
+      struct display_line *dl = &Dynarr_at (dyn, i);
+      total += compute_display_block_dynarr_usage(dl->display_blocks, ovstats);
+      total += compute_glyph_block_dynarr_usage  (dl->left_glyphs,    ovstats);
+      total += compute_glyph_block_dynarr_usage  (dl->right_glyphs,   ovstats);
+    }
+
+  return total;
+}
+
+int
+compute_line_start_cache_dynarr_usage (line_start_cache_dynarr *dyn,
+				       struct overhead_stats *ovstats)
+{
+  return dyn ? Dynarr_memory_usage (dyn, ovstats) : 0;
+}
+
+#endif /* MEMORY_USAGE_STATS */
+
+
+/***************************************************************************/
+/*									   */
+/*                              initialization                             */
+/*									   */
+/***************************************************************************/
+
+void
+init_redisplay (void)
+{
+  disable_preemption = 0;
+  preemption_count = 0;
+  max_preempts = INIT_MAX_PREEMPTS;
+
+#ifndef PDUMP
+  if (!initialized)
+#endif
+    {
+      cmotion_display_lines = Dynarr_new (display_line);
+      mode_spec_bufbyte_string = Dynarr_new (Bufbyte);
+      formatted_string_emchar_dynarr = Dynarr_new (Emchar);
+      formatted_string_extent_dynarr = Dynarr_new (EXTENT);
+      formatted_string_extent_start_dynarr = Dynarr_new (Bytecount);
+      formatted_string_extent_end_dynarr = Dynarr_new (Bytecount);
+      internal_cache = Dynarr_new (line_start_cache);
+      xzero (formatted_string_display_line);
+    }
+
+  /* window system is nil when in -batch mode */
+  if (!initialized || noninteractive)
+    return;
+
+  /* If the user wants to use a window system, we shouldn't bother
+     initializing the terminal.  This is especially important when the
+     terminal is so dumb that emacs gives up before and doesn't bother
+     using the window system.
+
+     If the DISPLAY environment variable is set, try to use X, and die
+     with an error message if that doesn't work.  */
+
+#ifdef HAVE_X_WINDOWS
+  if (!strcmp (display_use, "x"))
+    {
+      /* Some stuff checks this way early. */
+      Vwindow_system = Qx;
+      Vinitial_window_system = Qx;
+      return;
+    }
+#endif /* HAVE_X_WINDOWS */
+
+#ifdef HAVE_MS_WINDOWS
+  if (!strcmp (display_use, "mswindows"))
+    {
+      /* Some stuff checks this way early. */
+      Vwindow_system = Qmswindows;
+      Vinitial_window_system = Qmswindows;
+      return;
+    }
+#endif /* HAVE_MS_WINDOWS */
+
+#ifdef HAVE_TTY
+  /* If no window system has been specified, try to use the terminal.  */
+  if (!isatty (0))
+    {
+      stderr_out ("XEmacs: standard input is not a tty\n");
+      exit (1);
+    }
+
+  /* Look at the TERM variable */
+  if (!getenv ("TERM"))
+    {
+      stderr_out ("Please set the environment variable TERM; see tset(1).\n");
+      exit (1);
+    }
+
+  Vinitial_window_system = Qtty;
+  return;
+#else  /* not HAVE_TTY */
+  /* No DISPLAY specified, and no TTY support. */
+  stderr_out ("XEmacs: Cannot open display.\n\
+Please set the environmental variable DISPLAY to an appropriate value.\n");
+  exit (1);
+#endif
+  /* Unreached. */
+}
+
+void
+syms_of_redisplay (void)
+{
+  defsymbol (&Qcursor_in_echo_area, "cursor-in-echo-area");
+#ifndef INHIBIT_REDISPLAY_HOOKS
+  defsymbol (&Qpre_redisplay_hook, "pre-redisplay-hook");
+  defsymbol (&Qpost_redisplay_hook, "post-redisplay-hook");
+#endif /* INHIBIT_REDISPLAY_HOOKS */
+  defsymbol (&Qdisplay_warning_buffer, "display-warning-buffer");
+  defsymbol (&Qbar_cursor, "bar-cursor");
+  defsymbol (&Qredisplay_end_trigger_functions,
+	     "redisplay-end-trigger-functions");
+
+  DEFSUBR (Fredisplay_echo_area);
+  DEFSUBR (Fredraw_frame);
+  DEFSUBR (Fredisplay_frame);
+  DEFSUBR (Fredraw_device);
+  DEFSUBR (Fredisplay_device);
+  DEFSUBR (Fredraw_modeline);
+  DEFSUBR (Fforce_cursor_redisplay);
+}
+
+void
+reinit_vars_of_redisplay (void)
+{
+  updating_line_start_cache = 0;
+}
+
+void
+vars_of_redisplay (void)
+{
+  reinit_vars_of_redisplay ();
+
+#if 0
+  staticpro (&last_arrow_position);
+  staticpro (&last_arrow_string);
+  last_arrow_position = Qnil;
+  last_arrow_string = Qnil;
+#endif /* 0 */
+
+  /* #### Probably temporary */
+  DEFVAR_INT ("redisplay-cache-adjustment", &cache_adjustment /*
+\(Temporary) Setting this will impact the performance of the internal
+line start cache.
+*/ );
+  cache_adjustment = 2;
+
+  DEFVAR_INT_MAGIC ("pixel-vertical-clip-threshold", &vertical_clip /*
+Minimum pixel height for clipped bottom display line.
+A clipped line shorter than this won't be displayed.
+*/ ,
+		    redisplay_variable_changed);
+  vertical_clip = 5;
+
+  DEFVAR_INT_MAGIC ("pixel-horizontal-clip-threshold", &horizontal_clip /*
+Minimum visible area for clipped glyphs at right boundary.
+Clipped glyphs shorter than this won't be displayed.
+Only pixmap glyph instances are currently allowed to be clipped.
+*/ ,
+		    redisplay_variable_changed);
+  horizontal_clip = 5;
+
+  DEFVAR_LISP ("global-mode-string", &Vglobal_mode_string /*
+String displayed by modeline-format's "%m" specification.
+*/ );
+  Vglobal_mode_string = Qnil;
+
+  DEFVAR_LISP_MAGIC ("overlay-arrow-position", &Voverlay_arrow_position /*
+Marker for where to display an arrow on top of the buffer text.
+This must be the beginning of a line in order to work.
+See also `overlay-arrow-string'.
+*/ ,
+		     redisplay_variable_changed);
+  Voverlay_arrow_position = Qnil;
+
+  DEFVAR_LISP_MAGIC ("overlay-arrow-string", &Voverlay_arrow_string /*
+String to display as an arrow.  See also `overlay-arrow-position'.
+*/ ,
+		     redisplay_variable_changed);
+  Voverlay_arrow_string = Qnil;
+
+  DEFVAR_INT ("scroll-step", &scroll_step /*
+*The number of lines to try scrolling a window by when point moves out.
+If that fails to bring point back on frame, point is centered instead.
+If this is zero, point is always centered after it moves off screen.
+*/ );
+  scroll_step = 0;
+
+  DEFVAR_INT ("scroll-conservatively", &scroll_conservatively /*
+*Scroll up to this many lines, to bring point back on screen.
+*/ );
+  scroll_conservatively = 0;
+
+  DEFVAR_BOOL_MAGIC ("truncate-partial-width-windows",
+		     &truncate_partial_width_windows /*
+*Non-nil means truncate lines in all windows less than full frame wide.
+*/ ,
+		     redisplay_variable_changed);
+  truncate_partial_width_windows = 1;
+
+  DEFVAR_BOOL ("visible-bell", &visible_bell /*
+*Non-nil means try to flash the frame to represent a bell.
+*/ );
+  visible_bell = 0;
+
+  DEFVAR_BOOL ("no-redraw-on-reenter", &no_redraw_on_reenter /*
+*Non-nil means no need to redraw entire frame after suspending.
+A non-nil value is useful if the terminal can automatically preserve
+Emacs's frame display when you reenter Emacs.
+It is up to you to set this variable if your terminal can do that.
+*/ );
+  no_redraw_on_reenter = 0;
+
+  DEFVAR_LISP ("window-system", &Vwindow_system /*
+A symbol naming the window-system under which Emacs is running,
+such as `x', or nil if emacs is running on an ordinary terminal.
+
+Do not use this variable, except for GNU Emacs compatibility, as it
+gives wrong values in a multi-device environment.  Use `console-type'
+instead.
+*/ );
+  Vwindow_system = Qnil;
+
+  /* #### Temporary shit until window-system is eliminated. */
+  DEFVAR_CONST_LISP ("initial-window-system", &Vinitial_window_system /*
+DON'T TOUCH
+*/ );
+  Vinitial_window_system = Qnil;
+
+  DEFVAR_BOOL ("cursor-in-echo-area", &cursor_in_echo_area /*
+Non-nil means put cursor in minibuffer, at end of any message there.
+*/ );
+  cursor_in_echo_area = 0;
+
+  /* #### Shouldn't this be generalized as follows:
+
+     if nil, use block cursor.
+     if a number, use a bar cursor of that width.
+     Otherwise, use a 1-pixel bar cursor.
+
+     #### Or better yet, this variable should be trashed entirely
+     (use a Lisp-magic variable to maintain compatibility)
+     and a specifier `cursor-shape' added, which allows a block
+     cursor, a bar cursor, a flashing block or bar cursor,
+     maybe a caret cursor, etc. */
+
+  DEFVAR_LISP ("bar-cursor", &Vbar_cursor /*
+Use vertical bar cursor if non-nil.  If t width is 1 pixel, otherwise 2.
+*/ );
+  Vbar_cursor = Qnil;
+
+#ifndef INHIBIT_REDISPLAY_HOOKS
+  xxDEFVAR_LISP ("pre-redisplay-hook", &Vpre_redisplay_hook /*
+Function or functions to run before every redisplay.
+Functions on this hook must be careful to avoid signalling errors!
+*/ );
+  Vpre_redisplay_hook = Qnil;
+
+  xxDEFVAR_LISP ("post-redisplay-hook", &Vpost_redisplay_hook /*
+Function or functions to run after every redisplay.
+Functions on this hook must be careful to avoid signalling errors!
+*/ );
+  Vpost_redisplay_hook = Qnil;
+#endif /* INHIBIT_REDISPLAY_HOOKS */
+
+  DEFVAR_INT ("display-warning-tick", &display_warning_tick /*
+Bump this to tell the C code to call `display-warning-buffer'
+at next redisplay.  You should not normally change this; the function
+`display-warning' automatically does this at appropriate times.
+*/ );
+  display_warning_tick = 0;
+
+  DEFVAR_BOOL ("inhibit-warning-display", &inhibit_warning_display /*
+Non-nil means inhibit display of warning messages.
+You should *bind* this, not set it.  Any pending warning messages
+will be displayed when the binding no longer applies.
+*/ );
+  /* reset to 0 by startup.el after the splash screen has displayed.
+     This way, the warnings don't obliterate the splash screen. */
+  inhibit_warning_display = 1;
+
+  DEFVAR_LISP ("window-size-change-functions",
+               &Vwindow_size_change_functions /*
+Not currently implemented.
+Functions called before redisplay, if window sizes have changed.
+The value should be a list of functions that take one argument.
+Just before redisplay, for each frame, if any of its windows have changed
+size since the last redisplay, or have been split or deleted,
+all the functions in the list are called, with the frame as argument.
+*/ );
+  Vwindow_size_change_functions = Qnil;
+
+  DEFVAR_LISP ("window-scroll-functions", &Vwindow_scroll_functions /*
+Not currently implemented.
+Functions to call before redisplaying a window with scrolling.
+Each function is called with two arguments, the window
+and its new display-start position.  Note that the value of `window-end'
+is not valid when these functions are called.
+*/ );
+  Vwindow_scroll_functions = Qnil;
+
+  DEFVAR_LISP ("redisplay-end-trigger-functions",
+               &Vredisplay_end_trigger_functions /*
+See `set-window-redisplay-end-trigger'.
+*/ );
+  Vredisplay_end_trigger_functions = Qnil;
+
+  DEFVAR_BOOL ("column-number-start-at-one", &column_number_start_at_one /*
+*Non-nil means column display number starts at 1.
+*/ );
+  column_number_start_at_one = 0;
+}
+
+void
+specifier_vars_of_redisplay (void)
+{
+  DEFVAR_SPECIFIER ("left-margin-width", &Vleft_margin_width /*
+*Width of left margin.
+This is a specifier; use `set-specifier' to change it.
+*/ );
+  Vleft_margin_width = Fmake_specifier (Qnatnum);
+  set_specifier_fallback (Vleft_margin_width, list1 (Fcons (Qnil, Qzero)));
+  set_specifier_caching (Vleft_margin_width,
+			 slot_offset (struct window, left_margin_width),
+			 some_window_value_changed,
+			 slot_offset (struct frame, left_margin_width),
+			 margin_width_changed_in_frame);
+
+  DEFVAR_SPECIFIER ("right-margin-width", &Vright_margin_width /*
+*Width of right margin.
+This is a specifier; use `set-specifier' to change it.
+*/ );
+  Vright_margin_width = Fmake_specifier (Qnatnum);
+  set_specifier_fallback (Vright_margin_width, list1 (Fcons (Qnil, Qzero)));
+  set_specifier_caching (Vright_margin_width,
+			 slot_offset (struct window, right_margin_width),
+			 some_window_value_changed,
+			 slot_offset (struct frame, right_margin_width),
+			 margin_width_changed_in_frame);
+
+  DEFVAR_SPECIFIER ("minimum-line-ascent", &Vminimum_line_ascent /*
+*Minimum ascent height of lines.
+This is a specifier; use `set-specifier' to change it.
+*/ );
+  Vminimum_line_ascent = Fmake_specifier (Qnatnum);
+  set_specifier_fallback (Vminimum_line_ascent, list1 (Fcons (Qnil, Qzero)));
+  set_specifier_caching (Vminimum_line_ascent,
+			 slot_offset (struct window, minimum_line_ascent),
+			 some_window_value_changed,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("minimum-line-descent", &Vminimum_line_descent /*
+*Minimum descent height of lines.
+This is a specifier; use `set-specifier' to change it.
+*/ );
+  Vminimum_line_descent = Fmake_specifier (Qnatnum);
+  set_specifier_fallback (Vminimum_line_descent, list1 (Fcons (Qnil, Qzero)));
+  set_specifier_caching (Vminimum_line_descent,
+			 slot_offset (struct window, minimum_line_descent),
+			 some_window_value_changed,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("use-left-overflow", &Vuse_left_overflow /*
+*Non-nil means use the left outside margin as extra whitespace when
+displaying 'whitespace or 'inside-margin glyphs.
+This is a specifier; use `set-specifier' to change it.
+*/ );
+  Vuse_left_overflow = Fmake_specifier (Qboolean);
+  set_specifier_fallback (Vuse_left_overflow, list1 (Fcons (Qnil, Qnil)));
+  set_specifier_caching (Vuse_left_overflow,
+			 slot_offset (struct window, use_left_overflow),
+			 some_window_value_changed,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("use-right-overflow", &Vuse_right_overflow /*
+*Non-nil means use the right outside margin as extra whitespace when
+displaying 'whitespace or 'inside-margin glyphs.
+This is a specifier; use `set-specifier' to change it.
+*/ );
+  Vuse_right_overflow = Fmake_specifier (Qboolean);
+  set_specifier_fallback (Vuse_right_overflow, list1 (Fcons (Qnil, Qnil)));
+  set_specifier_caching (Vuse_right_overflow,
+			 slot_offset (struct window, use_right_overflow),
+			 some_window_value_changed,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("text-cursor-visible-p", &Vtext_cursor_visible_p /*
+*Non-nil means the text cursor is visible (this is usually the case).
+This is a specifier; use `set-specifier' to change it.
+*/ );
+  Vtext_cursor_visible_p = Fmake_specifier (Qboolean);
+  set_specifier_fallback (Vtext_cursor_visible_p, list1 (Fcons (Qnil, Qt)));
+  set_specifier_caching (Vtext_cursor_visible_p,
+			 slot_offset (struct window, text_cursor_visible_p),
+			 text_cursor_visible_p_changed,
+			 0, 0);
+
+}