--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/scrollbar.c	Mon Aug 13 08:45:50 2007 +0200
@@ -0,0 +1,982 @@
+/* Generic scrollbar implementation.
+   Copyright (C) 1994, 1995 Board of Trustees, University of Illinois.
+   Copyright (C) 1995 Free Software Foundation, Inc.
+   Copyright (C) 1995 Sun Microsystems, Inc.
+   Copyright (C) 1995 Darrell Kindred <dkindred+@cmu.edu>.
+
+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. */
+
+/* This file has been Mule-ized. */
+
+#include <config.h>
+#include "lisp.h"
+
+#include "buffer.h"
+#include "commands.h"
+#include "scrollbar.h"
+#include "device.h"
+#include "frame.h"
+#include "glyphs.h"
+#include "window.h"
+
+Lisp_Object Qinit_scrollbar_from_resources;
+
+Lisp_Object Qscrollbar_line_up;
+Lisp_Object Qscrollbar_line_down;
+Lisp_Object Qscrollbar_page_up;
+Lisp_Object Qscrollbar_page_down;
+Lisp_Object Qscrollbar_to_top;
+Lisp_Object Qscrollbar_to_bottom;
+Lisp_Object Qscrollbar_vertical_drag;
+
+Lisp_Object Qscrollbar_char_left;
+Lisp_Object Qscrollbar_char_right;
+Lisp_Object Qscrollbar_page_left;
+Lisp_Object Qscrollbar_page_right;
+Lisp_Object Qscrollbar_to_left;
+Lisp_Object Qscrollbar_to_right;
+Lisp_Object Qscrollbar_horizontal_drag;
+
+#define DEFAULT_SCROLLBAR_WIDTH 15
+#define DEFAULT_SCROLLBAR_HEIGHT 15
+
+/* Width of the scrollbar. */
+Lisp_Object Vscrollbar_width;
+
+/* Height of the scrollbar. */
+Lisp_Object Vscrollbar_height;
+
+Lisp_Object Vscrollbar_pointer_glyph;
+
+static void update_scrollbar_instance (struct window *w, int vertical,
+				       struct scrollbar_instance *instance);
+
+
+static void
+free_scrollbar_instance (struct scrollbar_instance *instance,
+			 struct frame *frame)
+{
+  if (!instance)
+    return;
+  else
+    {
+      struct device *d = XDEVICE (frame->device);
+
+      MAYBE_DEVMETH (d, free_scrollbar_instance, (instance));
+      xfree (instance);
+    }
+}
+
+static void
+free_window_mirror_scrollbars (struct window_mirror *mir)
+{
+  struct frame *f = mir->frame;
+  free_scrollbar_instance (mir->scrollbar_vertical_instance, f);
+  mir->scrollbar_vertical_instance = 0;
+  free_scrollbar_instance (mir->scrollbar_horizontal_instance, f);
+  mir->scrollbar_horizontal_instance = 0;
+}
+
+static struct window_mirror *
+free_scrollbars_loop (Lisp_Object window, struct window_mirror *mir)
+{
+  struct window_mirror *retval = NULL;
+
+  while (mir)
+    {
+      struct scrollbar_instance *vinst = mir->scrollbar_vertical_instance;
+      struct scrollbar_instance *hinst = mir->scrollbar_horizontal_instance;
+      struct frame *f;
+
+      assert (!NILP (window));
+      f = XFRAME (XWINDOW (window)->frame);
+
+      if (mir->vchild)
+	{
+	  retval = free_scrollbars_loop (XWINDOW (window)->vchild,
+					 mir->vchild);
+	}
+      else if (mir->hchild)
+	{
+	  retval = free_scrollbars_loop (XWINDOW (window)->hchild,
+					 mir->hchild);
+	}
+
+      if (retval != NULL)
+	return retval;
+
+      if (hinst || vinst)
+	free_window_mirror_scrollbars (mir);
+
+      mir = mir->next;
+      window = XWINDOW (window)->next;
+    }
+
+  return NULL;
+}
+
+/* Destroy all scrollbars associated with FRAME.  Only called from
+   delete_frame_internal.
+ */
+#define FREE_FRAME_SCROLLBARS_INTERNAL(cache)				\
+  do {									\
+    while (FRAME_SB_##cache (f))					\
+      {									\
+	struct scrollbar_instance *tofree = FRAME_SB_##cache (f);	\
+	FRAME_SB_##cache (f) = FRAME_SB_##cache (f)->next;		\
+	tofree->next = NULL;						\
+	free_scrollbar_instance (tofree, f);				\
+      }									\
+  } while (0)
+
+void
+free_frame_scrollbars (struct frame *f)
+{
+  if (!HAS_FRAMEMETH_P (f, create_scrollbar_instance))
+    return;
+
+  if (f->mirror_dirty)
+    update_frame_window_mirror (f);
+
+  free_scrollbars_loop (f->root_window, f->root_mirror);
+
+  FREE_FRAME_SCROLLBARS_INTERNAL (VCACHE);
+  FREE_FRAME_SCROLLBARS_INTERNAL (HCACHE);
+}
+#undef FREE_FRAME_SCROLLBARS_INTERNAL
+
+
+static struct scrollbar_instance *
+create_scrollbar_instance (struct frame *f, int vertical)
+{
+  struct device *d = XDEVICE (f->device);
+  struct scrollbar_instance *instance =
+    (struct scrollbar_instance *) xmalloc (sizeof (*instance));
+
+  memset (instance, 0, sizeof (*instance));
+  MAYBE_DEVMETH (d, create_scrollbar_instance, (f, vertical, instance));
+
+  return instance;
+}
+
+
+#define GET_SCROLLBAR_INSTANCE_INTERNAL(cache)				\
+  do {									\
+    if (FRAME_SB_##cache (f))						\
+      {									\
+        struct scrollbar_instance *retval = FRAME_SB_##cache (f);	\
+        FRAME_SB_##cache (f) = FRAME_SB_##cache (f)->next;		\
+        retval->next = NULL;						\
+        return retval;							\
+      }									\
+  } while (0)
+
+static struct scrollbar_instance *
+get_scrollbar_instance (struct frame *f, int vertical)
+{
+  /* Check if there are any available scrollbars already in existence. */
+  if (vertical)
+    GET_SCROLLBAR_INSTANCE_INTERNAL (VCACHE);
+  else
+    GET_SCROLLBAR_INSTANCE_INTERNAL (HCACHE);
+
+  return create_scrollbar_instance (f, vertical);
+}
+#undef GET_SCROLLBAR_INSTANCE_INTERNAL
+
+#define RELEASE_SCROLLBAR_INSTANCE_INTERNAL(cache)			\
+  do {									\
+    if (!FRAME_SB_##cache (f))						\
+      {									\
+	instance->next = NULL;						\
+	FRAME_SB_##cache (f) = instance;				\
+      }									\
+    else								\
+      {									\
+	instance->next = FRAME_SB_##cache (f);				\
+	FRAME_SB_##cache (f) = instance;				\
+      }									\
+  } while (0)
+
+static void
+release_scrollbar_instance (struct frame *f, int vertical,
+			    struct scrollbar_instance *instance)
+{
+  /* #### should we do "instance->mir = 0;" for safety? */
+  if (vertical)
+    RELEASE_SCROLLBAR_INSTANCE_INTERNAL (VCACHE);
+  else
+    RELEASE_SCROLLBAR_INSTANCE_INTERNAL (HCACHE);
+}
+#undef RELEASE_SCROLLBAR_INSTANCE_INTERNAL
+
+#ifdef MEMORY_USAGE_STATS
+
+int
+compute_scrollbar_instance_usage (struct device *d,
+				  struct scrollbar_instance *inst,
+				  struct overhead_stats *ovstats)
+{
+  int total = 0;
+
+  total += DEVMETH (d, compute_scrollbar_instance_usage, (d, inst, ovstats));
+
+  while (inst)
+    {
+      total += malloced_storage_size (inst, sizeof (*inst), ovstats);
+      inst = inst->next;
+    }
+
+  return total;
+}
+
+#endif /* MEMORY_USAGE_STATS */
+
+void
+update_window_scrollbars (struct window *w, struct window_mirror *mirror,
+			  int active, int horiz_only)
+{
+  struct frame *f = XFRAME (w->frame);
+  struct device *d = XDEVICE (f->device);
+
+  if (!HAS_DEVMETH_P (d, create_scrollbar_instance))
+    return;
+
+  in_display++;
+
+  /* It is possible for this to get called from the mirror update
+     routines.  In that case the structure is in an indeterminate
+     state but we know exactly what struct we are working with.  So we
+     pass it in in that case.  We also take advantage of it at some
+     other points where we know what the mirror struct is. */
+  if (!mirror)
+    mirror = find_window_mirror (w);
+
+  if (!mirror->scrollbar_vertical_instance && active)
+    mirror->scrollbar_vertical_instance = get_scrollbar_instance (f, 1);
+
+  if (!mirror->scrollbar_horizontal_instance && active)
+    mirror->scrollbar_horizontal_instance = get_scrollbar_instance (f, 0);
+
+  if (!horiz_only && mirror->scrollbar_vertical_instance)
+    {
+      int size = (active ? window_scrollbar_width (w) : 0);
+      struct scrollbar_instance *instance;
+
+      instance = mirror->scrollbar_vertical_instance;
+      instance->scrollbar_is_active = active;
+      instance->mirror = mirror;
+
+      if (active && size)
+	update_scrollbar_instance (w, 1, instance);
+      MAYBE_DEVMETH (d, update_scrollbar_instance_status,
+		     (w, active, size, instance));
+
+      if (!active)
+ 	{
+ 	  release_scrollbar_instance (f, 1, instance);
+ 	  mirror->scrollbar_vertical_instance = NULL;
+ 	}
+    }
+
+  if (mirror->scrollbar_horizontal_instance)
+    {
+      int size = (active ? window_scrollbar_height (w) : 0);
+      struct scrollbar_instance *instance;
+
+      instance = mirror->scrollbar_horizontal_instance;
+      instance->scrollbar_is_active = active;
+      instance->mirror = mirror;
+
+      if (active && size)
+	update_scrollbar_instance (w, 0, instance);
+      MAYBE_DEVMETH (d, update_scrollbar_instance_status,
+		     (w, active, size, instance));
+
+      if (!active)
+ 	{
+ 	  release_scrollbar_instance (f, 0, instance);
+ 	  mirror->scrollbar_horizontal_instance = NULL;
+ 	}
+    }
+
+  in_display--;
+}
+
+void
+release_window_mirror_scrollbars (struct window_mirror *mir)
+{
+  struct device *d = XDEVICE (mir->frame->device);
+
+  if (!HAS_DEVMETH_P (d, create_scrollbar_instance))
+    return;
+
+  if (mir->scrollbar_vertical_instance)
+    {
+      release_scrollbar_instance (mir->frame, 1,
+				  mir->scrollbar_vertical_instance);
+      MAYBE_DEVMETH (d, release_scrollbar_instance,
+		     (mir->scrollbar_vertical_instance));
+    }
+  mir->scrollbar_vertical_instance = 0;
+
+  if (mir->scrollbar_horizontal_instance)
+    {
+      release_scrollbar_instance (mir->frame, 0,
+				  mir->scrollbar_horizontal_instance);
+      MAYBE_DEVMETH (d, release_scrollbar_instance,
+		     (mir->scrollbar_horizontal_instance));
+    }
+  mir->scrollbar_horizontal_instance = 0;
+}
+
+/* This check needs to be done in the device-specific side. */
+#define UPDATE_DATA_FIELD(field, value) \
+  if (instance->field != value) {\
+    instance->field = value;\
+    instance->scrollbar_instance_changed = 1;\
+  }\
+
+/*
+ * If w->sb_point is on the top line then return w->sb_point else
+ * return w->start.  If flag, then return beginning point of line
+ * which w->sb_point lies on.
+ */
+static Bufpos
+scrollbar_point (struct window *w, int flag)
+{
+  Bufpos start_pos, end_pos, sb_pos;
+  Lisp_Object buf;
+  struct buffer *b;
+
+  if (NILP (w->buffer)) /* non-leaf window */
+    return 0;
+
+  start_pos = marker_position (w->start[CURRENT_DISP]);
+  sb_pos = marker_position (w->sb_point);
+
+  if (!flag && sb_pos < start_pos)
+    return start_pos;
+
+  buf = get_buffer (w->buffer, 0);
+  if (!NILP (buf))
+    b = XBUFFER (buf);
+  else
+    return start_pos;
+
+  if (flag)
+    end_pos = find_next_newline_no_quit (b, sb_pos, -1);
+  else
+    end_pos = find_next_newline_no_quit (b, start_pos, 1);
+
+  if (flag)
+    return end_pos;
+  else if (sb_pos > end_pos)
+    return start_pos;
+  else
+    return sb_pos;
+}
+
+/*
+ * Update a window's horizontal or vertical scrollbar.
+ */
+static void
+update_scrollbar_instance (struct window *w, int vertical,
+			   struct scrollbar_instance *instance)
+{
+  struct frame *f = XFRAME (w->frame);
+  struct device *d = XDEVICE (f->device);
+  struct buffer *b = XBUFFER (w->buffer);
+  Bufpos start_pos, end_pos, sb_pos;
+  int scrollbar_width = window_scrollbar_width (w);
+  int scrollbar_height = window_scrollbar_height (w);
+
+  int new_line_increment = -1, new_page_increment = -1;
+  int new_minimum = -1, new_maximum = -1;
+  int new_slider_size = -1, new_slider_position = -1;
+  int new_width = -1, new_height = -1, new_x = -1, new_y = -1;
+  struct window *new_window = 0;	/* kludge city */
+
+  end_pos = BUF_Z (b) - w->window_end_pos[CURRENT_DISP];
+  sb_pos = scrollbar_point (w, 0);
+  start_pos = sb_pos;
+
+  /* The end position must be strictly greater than the start
+     position, at least for the Motify scrollbar.  It shouldn't hurt
+     anything for other scrollbar implementations. */
+  if (end_pos <= start_pos)
+    end_pos = start_pos + 1;
+
+  if (vertical)
+    {
+      new_height = WINDOW_TEXT_HEIGHT (w);
+      new_width = scrollbar_width;
+    }
+  else
+    {
+      new_height = scrollbar_height;
+      new_width = WINDOW_TEXT_WIDTH (w);
+    }
+
+  /* If the height and width are not greater than 0, then later on the
+     Motif widgets will bitch and moan. */
+  if (new_height <= 0)
+    new_height = 1;
+  if (new_width <= 0)
+    new_width = 1;
+
+  assert (instance->mirror && XWINDOW (real_window(instance->mirror, 0)) == w);
+
+  /* Only character-based scrollbars are implemented at the moment.
+     Line-based will be implemented in the future. */
+
+  instance->scrollbar_is_active = 1;
+  new_line_increment = 1;
+  new_page_increment = 1;
+
+  if (!DEVMETH_OR_GIVEN (d, inhibit_scrollbar_thumb_size_change, (), 0))
+    {
+      int x_offset, y_offset;
+
+      /* Scrollbars are always the farthest from the text area. */
+      if (vertical)
+	{
+	  x_offset = (f->scrollbar_on_left
+		      ? WINDOW_LEFT (w)
+		      : WINDOW_RIGHT (w) - scrollbar_width);
+	  y_offset = WINDOW_TEXT_TOP (w) + f->scrollbar_y_offset;
+	}
+      else
+	{
+	  x_offset = WINDOW_TEXT_LEFT (w);
+	  y_offset = f->scrollbar_y_offset +
+	    (f->scrollbar_on_top
+	     ? WINDOW_TOP (w)
+	     : WINDOW_TEXT_BOTTOM (w) + window_bottom_toolbar_height (w));
+	}
+
+      new_x = x_offset;
+      new_y = y_offset;
+    }
+
+  /* A disabled scrollbar has its slider sized to the entire height of
+     the scrollbar.  Currently the minibuffer scrollbar is
+     disabled. */
+  if (!MINI_WINDOW_P (w) && vertical)
+    {
+      if (!DEVMETH_OR_GIVEN (d, inhibit_scrollbar_thumb_size_change, (), 0))
+	{
+	  new_minimum = BUF_BEGV (b);
+	  new_maximum = max (BUF_ZV (b), new_minimum + 1);
+	  new_slider_size = min ((end_pos - start_pos),
+				 (new_maximum - new_minimum));
+	  new_slider_position = sb_pos;
+	  new_window = w;
+	}
+    }
+  else if (!MINI_WINDOW_P (w))
+    {
+      /* The minus one is to account for the truncation glyph. */
+      int wcw = window_char_width (w, 0) - 1;
+      int max_width, max_slide;
+
+      if (w->max_line_len < wcw)
+	{
+	  max_width = 1;
+	  max_slide = 1;
+	  wcw = 1;
+	}
+      else
+	{
+	  max_width = w->max_line_len + 2;
+	  max_slide = max_width - wcw;
+	}
+
+      new_minimum = 0;
+      new_maximum = max_width;
+      new_slider_size = wcw;
+      new_slider_position = min (w->hscroll, max_slide);
+    }
+  else
+    {
+      new_minimum = 1;
+      new_maximum = 2;
+      new_slider_size = 1;
+      new_slider_position = 1;
+      instance->scrollbar_is_active = 0;
+    }
+
+  DEVMETH (d, update_scrollbar_instance_values, (w, instance,
+						 new_line_increment,
+						 new_page_increment,
+						 new_minimum,
+						 new_maximum,
+						 new_slider_size,
+						 new_slider_position,
+						 new_width, new_height,
+						 new_x, new_y));
+}
+
+void
+init_frame_scrollbars (struct frame *f)
+{
+  struct device *d = XDEVICE (f->device);
+
+  if (HAS_DEVMETH_P (d, create_scrollbar_instance))
+    {
+      Lisp_Object frame = Qnil;
+
+      XSETFRAME (frame, f);
+      call_critical_lisp_code (XDEVICE (FRAME_DEVICE (f)),
+			       Qinit_scrollbar_from_resources,
+			       frame);
+    }
+}
+
+void
+init_device_scrollbars (struct device *d)
+{
+  if (HAS_DEVMETH_P (d, create_scrollbar_instance))
+    {
+      Lisp_Object device = Qnil;
+
+      XSETDEVICE (device, d);
+      call_critical_lisp_code (d,
+			       Qinit_scrollbar_from_resources,
+			       device);
+    }
+}
+
+void
+init_global_scrollbars (struct device *d)
+{
+  if (HAS_DEVMETH_P (d, create_scrollbar_instance))
+    {
+      call_critical_lisp_code (d,
+			       Qinit_scrollbar_from_resources,
+			       Qglobal);
+    }
+}
+
+
+/* This function is called as a result of a change to the
+   `scrollbar-width' specifier. */
+static void
+scrollbar_width_changed_in_frame (Lisp_Object specifier, struct frame *f,
+				  Lisp_Object oldval)
+{
+  MAYBE_FRAMEMETH (f, scrollbar_width_changed_in_frame,
+		   (specifier, f, oldval));
+}
+
+/* This function is called as a result of a change to the
+   `scrollbar-height' specifier.  */
+static void
+scrollbar_height_changed_in_frame (Lisp_Object specifier, struct frame *f,
+				   Lisp_Object oldval)
+{
+  MAYBE_FRAMEMETH (f, scrollbar_height_changed_in_frame,
+		   (specifier, f, oldval));
+}
+
+/* This function is called as a result of a change to the
+   `scrollbar-pointer' glyph.  */
+static void
+scrollbar_pointer_changed_in_window (Lisp_Object specifier, struct window *w,
+				     Lisp_Object oldval)
+{
+  struct frame *f = XFRAME (WINDOW_FRAME (w));
+
+  if (f->init_finished)
+    MAYBE_FRAMEMETH (f, scrollbar_pointer_changed_in_window, (w));
+}
+
+/* ####
+
+   All of the following stuff is functions that handle scrollbar
+   actions.  All of it should be moved into Lisp.  This may require
+   adding some badly-needed primitives. */
+
+/********** vertical scrollbar stuff **********/
+
+/*
+ * If the original point is still visible, put the cursor back there.
+ * Otherwise, when scrolling down stick it at the beginning of the
+ * first visible line and when scrolling up stick it at the beginning
+ * of the last visible line.
+ */
+
+/* #### This function should be moved into Lisp */
+static void
+scrollbar_reset_cursor (Lisp_Object win, Lisp_Object orig_pt)
+{
+  /* When this function is called we know that start is already
+     accurate.  We know this because either set-window-start or
+     recenter was called immediately prior to it being called. */
+  Lisp_Object buf;
+  Bufpos start_pos = XINT (Fwindow_start (win));
+  Bufpos ptint = XINT (orig_pt);
+  struct window *w = XWINDOW (win);
+  int selected = ((w == XWINDOW (Fselected_window (XFRAME (w->frame)->device)))
+		  ? 1
+		  : 0);
+
+  buf = Fwindow_buffer (win);
+  if (NILP (buf))
+    return;	/* the window was deleted out from under us */
+
+  if (ptint < XINT (Fwindow_start (win)))
+    {
+      if (selected)
+	Fgoto_char (make_int (start_pos), buf);
+      else
+	Fset_window_point (win, make_int (start_pos));
+    }
+  else if (!point_would_be_visible (XWINDOW (win), start_pos, ptint))
+    {
+      Fmove_to_window_line (make_int (-1), win);
+
+      if (selected)
+	Fbeginning_of_line (Qnil, buf);
+      else
+	{
+	  /* #### Taken from forward-line. */
+	  Bufpos pos;
+
+	  pos = find_next_newline (XBUFFER (buf),
+				   marker_position (w->pointm[CURRENT_DISP]),
+				   -1);
+	  Fset_window_point (win, make_int (pos));
+	}
+    }
+  else
+    {
+      if (selected)
+	Fgoto_char (orig_pt, buf);
+      else
+	Fset_window_point (win, orig_pt);
+    }
+}
+
+DEFUN ("scrollbar-line-up", Fscrollbar_line_up, Sscrollbar_line_up, 1, 1, 0 /*
+Function called when the line-up arrow on the scrollbar is clicked.
+This is the little arrow at the top of the scrollbar.  One argument, the
+scrollbar's window.  You can advise this function to change the scrollbar
+behavior.
+*/ )
+     (window)
+     Lisp_Object window;
+{
+  CHECK_LIVE_WINDOW (window);
+  window_scroll (window, make_int (1), -1, ERROR_ME_NOT);
+  zmacs_region_stays = 1;
+  return Qnil;
+}
+
+DEFUN ("scrollbar-line-down", Fscrollbar_line_down, Sscrollbar_line_down,
+       1, 1, 0 /*
+Function called when the line-down arrow on the scrollbar is clicked.
+This is the little arrow at the bottom of the scrollbar.  One argument, the
+scrollbar's window.  You can advise this function to change the scrollbar
+behavior.
+*/ )
+     (window)
+     Lisp_Object window;
+{
+  CHECK_LIVE_WINDOW (window);
+  window_scroll (window, make_int (1), 1, ERROR_ME_NOT);
+  zmacs_region_stays = 1;
+  return Qnil;
+}
+
+DEFUN ("scrollbar-page-up", Fscrollbar_page_up, Sscrollbar_page_up,
+       1, 1, 0 /*
+Function called when the user gives the \"page-up\" scrollbar action.
+(The way this is done can vary from scrollbar to scrollbar.) One argument,
+a cons containing the scrollbar's window and a value (#### document me!
+This value is nil for Motif/Lucid scrollbars and a number for Athena
+scrollbars).  You can advise this function to change the scrollbar
+behavior.
+*/ )
+     (object)
+     Lisp_Object object;
+{
+  Lisp_Object window = Fcar (object);
+
+  CHECK_LIVE_WINDOW (window);
+  /* Motif and Athena scrollbars behave differently, but in accordance
+     with their standard behaviors.  It is not possible to hide the
+     differences down in lwlib because knowledge of XEmacs buffer and
+     cursor motion routines is necessary. */
+#if defined (LWLIB_SCROLLBARS_MOTIF) || defined (LWLIB_SCROLLBARS_LUCID)
+  window_scroll (window, Qnil, -1, ERROR_ME_NOT);
+#else /* Athena */
+  {
+    Bufpos bufpos;
+    Lisp_Object value = Fcdr (object);
+
+    CHECK_INT (value);
+    Fmove_to_window_line (Qzero, window);
+    /* can't use Fvertical_motion() because it moves the buffer point
+       rather than the window's point.
+
+       #### It does?  Why does it take a window argument then? */
+    bufpos = vmotion (XWINDOW (window), XINT (Fwindow_point (window)),
+		      XINT (value), 0);
+    Fset_window_point (window, make_int (bufpos));
+    Frecenter (Qzero, window);
+  }
+#endif /* Athena */
+  zmacs_region_stays = 1;
+  return Qnil;
+}
+
+DEFUN ("scrollbar-page-down", Fscrollbar_page_down, Sscrollbar_page_down,
+       1, 1, 0 /*
+Function called when the user gives the \"page-down\" scrollbar action.
+(The way this is done can vary from scrollbar to scrollbar.) One argument,
+a cons containing the scrollbar's window and a value (#### document me!
+This value is nil for Motif/Lucid scrollbars and a number for Athena
+scrollbars).  You can advise this function to change the scrollbar
+behavior.
+*/ )
+     (object)
+     Lisp_Object object;
+{
+  Lisp_Object window = Fcar (object);
+
+  CHECK_LIVE_WINDOW (window);
+  /* Motif and Athena scrollbars behave differently, but in accordance
+     with their standard behaviors.  It is not possible to hide the
+     differences down in lwlib because knowledge of XEmacs buffer and
+     cursor motion routines is necessary. */
+#if defined (LWLIB_SCROLLBARS_MOTIF) || defined (LWLIB_SCROLLBARS_LUCID)
+  window_scroll (window, Qnil, 1, ERROR_ME_NOT);
+#else /* Athena */
+  {
+    Lisp_Object value = Fcdr (object);
+    CHECK_INT (value);
+    Fmove_to_window_line (value, window);
+    Frecenter (Qzero, window);
+  }
+#endif /* Athena */
+  zmacs_region_stays = 1;
+  return Qnil;
+}
+
+DEFUN ("scrollbar-to-top", Fscrollbar_to_top, Sscrollbar_to_top,
+       1, 1, 0 /*
+Function called when the user gives the \"to-top\" scrollbar action.
+(The way this is done can vary from scrollbar to scrollbar.). One argument,
+the scrollbar's window.  You can advise this function to change the
+scrollbar behavior.
+*/ )
+     (window)
+     Lisp_Object window;
+{
+  Lisp_Object orig_pt;
+
+  orig_pt = Fwindow_point (window);
+  Fset_window_point (window, Fpoint_min (Fwindow_buffer (window)));
+  Frecenter (Qzero, window);
+  scrollbar_reset_cursor (window, orig_pt);
+  zmacs_region_stays = 1;
+  return Qnil;
+}
+
+DEFUN ("scrollbar-to-bottom", Fscrollbar_to_bottom, Sscrollbar_to_bottom,
+       1, 1, 0 /*
+Function called when the user gives the \"to-bottom\" scrollbar action.
+(The way this is done can vary from scrollbar to scrollbar.). One argument,
+the scrollbar's window.  You can advise this function to change the
+scrollbar behavior.
+*/ )
+     (window)
+     Lisp_Object window;
+{
+  Lisp_Object orig_pt;
+
+  orig_pt = Fwindow_point (window);
+  Fset_window_point (window, Fpoint_max (Fwindow_buffer (window)));
+  Frecenter (Qzero, window);
+  scrollbar_reset_cursor (window, orig_pt);
+  zmacs_region_stays = 1;
+  return Qnil;
+}
+
+DEFUN ("scrollbar-vertical-drag", Fscrollbar_vertical_drag,
+       Sscrollbar_vertical_drag, 1, 1, 0 /*
+Function called when the user drags the vertical scrollbar thumb.
+One argument, a cons containing the scrollbar's window and a value
+(#### document me!).  You can advise this function to change the
+scrollbar behavior.
+*/ )
+     (object)
+     Lisp_Object object;
+{
+  Bufpos start_pos;
+  Lisp_Object orig_pt;
+  Lisp_Object window = Fcar (object);
+  Lisp_Object value = Fcdr (object);
+
+  orig_pt = Fwindow_point (window);
+  Fset_marker (XWINDOW (window)->sb_point, value, Fwindow_buffer (window));
+  start_pos = scrollbar_point (XWINDOW (window), 1);
+  Fset_window_start (window, make_int (start_pos), Qnil);
+  scrollbar_reset_cursor (window, orig_pt);
+  zmacs_region_stays = 1;
+  return Qnil;
+}
+
+DEFUN ("scrollbar-set-hscroll", Fscrollbar_set_hscroll, Sscrollbar_set_hscroll,
+       2, 2, 0 /*
+Sets WINDOW's hscroll position to VALUE.
+This ensures that VALUE is in the proper range for the horizontal scrollbar.
+*/ )
+	(window, value)
+	Lisp_Object window, value;
+{
+  struct window *w;
+  int hscroll, wcw, max_len;
+
+  CHECK_LIVE_WINDOW (window);
+  if (!EQ (value, Qmax))
+    CHECK_INT (value);
+
+  w = XWINDOW (window);
+  wcw = window_char_width (w, 0) - 1;
+  max_len = w->max_line_len + 1;
+
+  if (EQ (value, Qmax) || (XINT (value) > (max_len - wcw)))
+    hscroll = max_len - wcw;
+  else
+    hscroll = XINT (value);
+
+  /* Can't allow this out of set-window-hscroll's acceptable range. */
+  if (hscroll < 0)
+    hscroll = 0;
+  else if (hscroll >= (1 << (SHORTBITS - 1)))
+    hscroll = (1 << (SHORTBITS - 1)) - 1;
+
+  if (hscroll != w->hscroll)
+    Fset_window_hscroll (window, make_int (hscroll));
+
+  return Qnil;
+}
+
+
+/************************************************************************/
+/*                            initialization                            */
+/************************************************************************/
+
+void
+syms_of_scrollbar (void)
+{
+  defsymbol (&Qscrollbar_line_up, "scrollbar-line-up");
+  defsymbol (&Qscrollbar_line_down, "scrollbar-line-down");
+  defsymbol (&Qscrollbar_page_up, "scrollbar-page-up");
+  defsymbol (&Qscrollbar_page_down, "scrollbar-page-down");
+  defsymbol (&Qscrollbar_to_top, "scrollbar-to-top");
+  defsymbol (&Qscrollbar_to_bottom, "scrollbar-to-bottom");
+  defsymbol (&Qscrollbar_vertical_drag, "scrollbar-vertical-drag");
+  
+  defsymbol (&Qscrollbar_char_left, "scrollbar-char-left");
+  defsymbol (&Qscrollbar_char_right, "scrollbar-char-right");
+  defsymbol (&Qscrollbar_page_left, "scrollbar-page-left");
+  defsymbol (&Qscrollbar_page_right, "scrollbar-page-right");
+  defsymbol (&Qscrollbar_to_left, "scrollbar-to-left");
+  defsymbol (&Qscrollbar_to_right, "scrollbar-to-right");
+  defsymbol (&Qscrollbar_horizontal_drag, "scrollbar-horizontal-drag");
+
+  defsymbol (&Qinit_scrollbar_from_resources, "init-scrollbar-from-resources");
+
+  /* #### All these functions should be moved into Lisp.
+     See comment above. */
+  defsubr (&Sscrollbar_line_up);
+  defsubr (&Sscrollbar_line_down);
+  defsubr (&Sscrollbar_page_up);
+  defsubr (&Sscrollbar_page_down);
+  defsubr (&Sscrollbar_to_top);
+  defsubr (&Sscrollbar_to_bottom);
+  defsubr (&Sscrollbar_vertical_drag);
+
+  defsubr (&Sscrollbar_set_hscroll);
+}
+
+void
+vars_of_scrollbar (void)
+{
+  DEFVAR_LISP ("scrollbar-pointer-glyph", &Vscrollbar_pointer_glyph /*
+*The shape of the mouse-pointer when over a scrollbar.
+This is a glyph; use `set-glyph-image' to change it.
+If unspecified in a particular domain, the window-system-provided
+default pointer is used.
+*/ );
+
+  Fprovide (intern ("scrollbar"));
+}
+
+void
+specifier_vars_of_scrollbar (void)
+{
+  DEFVAR_SPECIFIER ("scrollbar-width", &Vscrollbar_width /*
+*Width of vertical scrollbars.
+This is a specifier; use `set-specifier' to change it.
+*/ );
+  Vscrollbar_width = Fmake_specifier (Qnatnum);
+  set_specifier_fallback
+    (Vscrollbar_width,
+     list1 (Fcons (Qnil, make_int (DEFAULT_SCROLLBAR_WIDTH))));
+  set_specifier_caching (Vscrollbar_width,
+			 slot_offset (struct window,
+				      scrollbar_width),
+			 some_window_value_changed,
+			 slot_offset (struct frame,
+				      scrollbar_width),
+			 scrollbar_width_changed_in_frame);
+
+  DEFVAR_SPECIFIER ("scrollbar-height", &Vscrollbar_height /*
+*Height of horizontal scrollbars.
+This is a specifier; use `set-specifier' to change it.
+*/ );
+  Vscrollbar_height = Fmake_specifier (Qnatnum);
+  set_specifier_fallback
+    (Vscrollbar_height,
+     list1 (Fcons (Qnil, make_int (DEFAULT_SCROLLBAR_HEIGHT))));
+  set_specifier_caching (Vscrollbar_height,
+			 slot_offset (struct window,
+				      scrollbar_height),
+			 some_window_value_changed,
+			 slot_offset (struct frame,
+				      scrollbar_height),
+			 scrollbar_height_changed_in_frame);
+}
+
+void
+complex_vars_of_scrollbar (void)
+{
+  Vscrollbar_pointer_glyph = Fmake_glyph_internal (Qpointer);
+
+  set_specifier_caching (XGLYPH (Vscrollbar_pointer_glyph)->image,
+			 slot_offset (struct window,
+				      scrollbar_pointer),
+			 scrollbar_pointer_changed_in_window,
+			 0, 0);
+}