--- a/src/scrollbar-msw.c	Mon Aug 13 11:01:58 2007 +0200
+++ b/src/scrollbar-msw.c	Mon Aug 13 11:03:08 2007 +0200
@@ -24,7 +24,6 @@
 /* Synched up with: Not in FSF. */
 
 #include <config.h>
-#include <limits.h>
 #include "lisp.h"
 
 #include "console-msw.h"
@@ -35,13 +34,11 @@
 #include "specifier.h"
 #include "window.h"
 
-/* We use a similar sort of vertical scrollbar drag hack for mswindows
- * scrollbars as is used for Motif or Lucid scrollbars under X.
- * We do character-based instead of line-based scrolling, which can mean that
- * without the hack it is impossible to drag to the end of a buffer. */
-#define VERTICAL_SCROLLBAR_DRAG_HACK
-
-static int vertical_drag_in_progress = 0;
+/* This has really different semantics in Windows than in Motif.
+   There's no corresponding method; we just do not change slider
+   size while dragging. It makes the scrollbar look smother and
+   prevents some weird behavior when scrolled near the bottom */
+static int inhibit_slider_size_change = 0;
 
 static void
 mswindows_create_scrollbar_instance (struct frame *f, int vertical,
@@ -62,7 +59,6 @@
 		 CW_USEDEFAULT, CW_USEDEFAULT,
 		 FRAME_MSWINDOWS_HANDLE (f),
 		 NULL, NULL, NULL);
-  SCROLLBAR_MSW_INFO (sb).cbSize = sizeof(SCROLLINFO);
   SCROLLBAR_MSW_INFO (sb).fMask = SIF_ALL;
   GetScrollInfo(SCROLLBAR_MSW_HANDLE (sb), SB_CTL,
 		&SCROLLBAR_MSW_INFO (sb));
@@ -114,8 +110,10 @@
 					    int new_scrollbar_x,
 					    int new_scrollbar_y)
 {
+  struct frame *f;
   int pos_changed = 0;
-  int vert = GetWindowLong (SCROLLBAR_MSW_HANDLE (sb), GWL_STYLE) & SBS_VERT;
+
+  f = XFRAME (w->frame);
 
 #if 0
   stderr_out ("[%d, %d], page = %d, pos = %d, inhibit = %d\n", new_minimum, new_maximum,
@@ -124,23 +122,17 @@
 
   /* These might be optimized, but since at least one will change at each
      call, it's probably not worth it. */
+  SCROLLBAR_MSW_INFO (sb).cbSize = sizeof(SCROLLINFO);
   SCROLLBAR_MSW_INFO (sb).nMin = new_minimum;
   SCROLLBAR_MSW_INFO (sb).nMax = new_maximum;
-  SCROLLBAR_MSW_INFO (sb).nPage = new_slider_size + 1; /* +1 for DISABLENOSCROLL */
+  SCROLLBAR_MSW_INFO (sb).nPage = new_slider_size + 1; /* for DISABLENOSCROLL */
   SCROLLBAR_MSW_INFO (sb).nPos = new_slider_position;
-#ifndef VERTICAL_SCROLLBAR_DRAG_HACK
-  SCROLLBAR_MSW_INFO (sb).fMask = ((vert && vertical_drag_in_progress)
+  SCROLLBAR_MSW_INFO (sb).fMask = (inhibit_slider_size_change 
 				   ? SIF_RANGE | SIF_POS
 				   : SIF_ALL | SIF_DISABLENOSCROLL);
-#else
-  SCROLLBAR_MSW_INFO (sb).fMask = SIF_ALL | SIF_DISABLENOSCROLL;
-
-  /* Ignore XEmacs' requests to update the thumb position and size; they don't
-   * bear any relation to reality because we're reporting made-up positions */
-  if (!(vert && vertical_drag_in_progress))
-#endif
-    SetScrollInfo (SCROLLBAR_MSW_HANDLE (sb), SB_CTL, &SCROLLBAR_MSW_INFO (sb),
-		   TRUE);
+  
+  SetScrollInfo(SCROLLBAR_MSW_HANDLE (sb), SB_CTL, &SCROLLBAR_MSW_INFO (sb),
+		!pos_changed);
 
   UPDATE_POS_FIELD (scrollbar_x);
   UPDATE_POS_FIELD (scrollbar_y);
@@ -179,13 +171,14 @@
   struct scrollbar_instance *sb;
   SCROLLINFO scrollinfo;
   int vert = GetWindowLong (hwnd, GWL_STYLE) & SBS_VERT;
-  int value;
 
   sb = (struct scrollbar_instance *)GetWindowLong (hwnd, GWL_USERDATA);
   win = real_window (sb->mirror, 1);
   frame = XWINDOW (win)->frame;
   f = XFRAME (frame);
 
+  inhibit_slider_size_change = code == SB_THUMBTRACK;
+
   /* SB_LINEDOWN == SB_CHARLEFT etc. This is the way they will
      always be - any Windows is binary compatible backward with 
      old programs */
@@ -228,107 +221,16 @@
     case SB_THUMBTRACK:
     case SB_THUMBPOSITION:
       scrollinfo.cbSize = sizeof(SCROLLINFO);
-      scrollinfo.fMask = SIF_ALL;
+      scrollinfo.fMask = SIF_TRACKPOS;
       GetScrollInfo (hwnd, SB_CTL, &scrollinfo);
-      vertical_drag_in_progress = vert;
-#ifdef VERTICAL_SCROLLBAR_DRAG_HACK
-      if (vert && (scrollinfo.nTrackPos > scrollinfo.nPos))
-        /* new buffer position =
-	 *  buffer position at start of drag +
-	 *   ((text remaining in buffer at start of drag) *
-	 *    (amount that the thumb has been moved) /
-	 *    (space that remained past end of the thumb at start of drag)) */
-	value = (int)
-	  (scrollinfo.nPos
-	   + (((double)
-	      (scrollinfo.nMax - scrollinfo.nPos)
-	       * (scrollinfo.nTrackPos - scrollinfo.nPos))
-	      / (scrollinfo.nMax - scrollinfo.nPage - scrollinfo.nPos)))
-	  - 2;	/* ensure that the last line doesn't disappear off screen */
-      else
-#endif
-        value = scrollinfo.nTrackPos;
       mswindows_enqueue_misc_user_event
 	(frame,
 	 vert ? Qscrollbar_vertical_drag : Qscrollbar_horizontal_drag,
-	 Fcons (win, make_int (value)));
-      break;
-
-    case SB_ENDSCROLL:
-#ifdef VERTICAL_SCROLLBAR_DRAG_HACK
-      if (vertical_drag_in_progress)
-	/* User has just dropped the thumb - finally update it */
-	SetScrollInfo (SCROLLBAR_MSW_HANDLE (sb), SB_CTL,
-		       &SCROLLBAR_MSW_INFO (sb), TRUE);
-#endif
-      vertical_drag_in_progress = 0;
+	 Fcons (win, make_int (scrollinfo.nTrackPos)));
       break;
     }
 }
 
-static int
-can_scroll(struct scrollbar_instance* scrollbar)
-{
-  return scrollbar != NULL
-	&& IsWindowVisible (SCROLLBAR_MSW_HANDLE (scrollbar))
-	&& IsWindowEnabled (SCROLLBAR_MSW_HANDLE (scrollbar));
-}
-
-int
-mswindows_handle_mousewheel_event (Lisp_Object frame, int keys, int delta)
-{
-  int hasVertBar, hasHorzBar;	/* Indicates prescence of scroll bars */
-  unsigned wheelScrollLines = 0; /* Number of lines per wheel notch */
-
-  /* Find the currently selected window */
-  Lisp_Object win = FRAME_SELECTED_WINDOW (XFRAME (frame));
-  struct window* w = XWINDOW (win);
-  struct window_mirror* mirror = find_window_mirror (w);
-
-  /* Check that there is something to scroll */
-  hasVertBar = can_scroll (mirror->scrollbar_vertical_instance);
-  hasHorzBar = can_scroll (mirror->scrollbar_horizontal_instance);
-  if (!hasVertBar && !hasHorzBar)
-    return FALSE;
-
-  /* No support for panning and zooming, so ignore */
-  if (keys & (MK_SHIFT | MK_CONTROL))
-    return FALSE;
-
-  /* Get the number of lines per wheel delta */
-  SystemParametersInfo (SPI_GETWHEELSCROLLLINES, 0, &wheelScrollLines, 0);
-
-  /* Calculate the amount to scroll */
-  if (wheelScrollLines == WHEEL_PAGESCROLL)
-    {
-      /* Scroll by a page */
-      Lisp_Object function;
-      if (hasVertBar)
-	function = delta > 0 ? Qscrollbar_page_up : Qscrollbar_page_down;
-      else
-	function = delta > 0 ? Qscrollbar_page_left : Qscrollbar_page_right;
-      mswindows_enqueue_misc_user_event (frame, function, Fcons (win, Qnil));
-    }
-  else /* Scroll by a number of lines */
-    {
-      /* Calc the number of lines to scroll */
-      int toScroll = MulDiv (delta, wheelScrollLines, WHEEL_DELTA);
-
-      /* Do the scroll */
-      Lisp_Object function;
-      if (hasVertBar)
-	function = delta > 0 ? Qscrollbar_line_up : Qscrollbar_line_down;
-      else
-	function = delta > 0 ? Qscrollbar_char_left : Qscrollbar_char_right;
-      if (toScroll < 0)
-	toScroll = -toScroll;
-      while (toScroll--)
-	mswindows_enqueue_misc_user_event (frame, function, win);
-    }
-
-  return TRUE;
-}
-
 #ifdef MEMORY_USAGE_STATS
 
 static int