Merged in changes from CVS trunk.

Patches applied:

 * miles@gnu.org--gnu-2004/emacs--cvs-trunk--0--patch-753
   Update from CVS

 * miles@gnu.org--gnu-2004/emacs--cvs-trunk--0--patch-754
   Merge from gnus--rel--5.10

 * miles@gnu.org--gnu-2004/emacs--cvs-trunk--0--patch-755
   Update from CVS

 * miles@gnu.org--gnu-2004/emacs--cvs-trunk--0--patch-756
   Update from CVS

 * miles@gnu.org--gnu-2004/emacs--cvs-trunk--0--patch-757
   Update from CVS

 * miles@gnu.org--gnu-2004/gnus--rel--5.10--patch-81
   Merge from emacs--cvs-trunk--0

 * miles@gnu.org--gnu-2004/gnus--rel--5.10--patch-82
   Update from CVS

git-archimport-id: lorentey@elte.hu--2004/emacs--multi-tty--0--patch-279

1 files changed, 56 insertions, 30 deletions

diff --git a/src/window.c b/src/window.c
index e3beb4b10a5..ff536be55aa 100644
--- a/src/window.c
+++ b/src/window.c
@@ -4673,30 +4673,32 @@ window_scroll_pixel_based (window, n, whole, noerror)
      not including the height of the header line if any.  */
   it.current_y = it.vpos = 0;
 
-  /* Preserve the screen position if we should.  */
-  if (preserve_y >= 0)
+  /* Move PT out of scroll margins.
+     This code wants current_y to be zero at the window start position
+     even if there is a header line.  */
+  this_scroll_margin = max (0, scroll_margin);
+  this_scroll_margin = min (this_scroll_margin, XFASTINT (w->total_lines) / 4);
+  this_scroll_margin *= FRAME_LINE_HEIGHT (it.f);
+
+  if (n > 0)
     {
-      /* If we have a header line, take account of it.  */
-      if (WINDOW_WANTS_HEADER_LINE_P (w))
-        preserve_y -= CURRENT_HEADER_LINE_HEIGHT (w);
+      /* We moved the window start towards ZV, so PT may be now
+         in the scroll margin at the top.  */
+      move_it_to (&it, PT, -1, -1, -1, MOVE_TO_POS);
+      if (IT_CHARPOS (it) == PT && it.current_y >= this_scroll_margin)
+        /* We found PT at a legitimate height.  Leave it alone.  */
+        ;
+      else if (preserve_y >= 0)
+        {
+          /* If we have a header line, take account of it.  */
+          if (WINDOW_WANTS_HEADER_LINE_P (w))
+            preserve_y -= CURRENT_HEADER_LINE_HEIGHT (w);
 
-      move_it_to (&it, -1, -1, preserve_y, -1, MOVE_TO_Y);
-      SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
-    }
-  else
-    {
-      /* Move PT out of scroll margins.
-         This code wants current_y to be zero at the window start position
-         even if there is a header line.  */
-      this_scroll_margin = max (0, scroll_margin);
-      this_scroll_margin = min (this_scroll_margin, XFASTINT (w->total_lines) / 4);
-      this_scroll_margin *= FRAME_LINE_HEIGHT (it.f);
-
-      if (n > 0)
+          move_it_to (&it, -1, -1, preserve_y, -1, MOVE_TO_Y);
+          SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
+        }
+      else
         {
-          /* We moved the window start towards ZV, so PT may be now
-             in the scroll margin at the top.  */
-          move_it_to (&it, PT, -1, -1, -1, MOVE_TO_POS);
           while (it.current_y < this_scroll_margin)
             {
               int prev = it.current_y;
@@ -4706,22 +4708,44 @@ window_scroll_pixel_based (window, n, whole, noerror)
             }
           SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
         }
-      else if (n < 0)
-        {
-          int charpos, bytepos;
+    }
+  else if (n < 0)
+    {
+      int charpos, bytepos;
+
+      /* Save our position, for the preserve_y case.  */
+      charpos = IT_CHARPOS (it);
+      bytepos = IT_BYTEPOS (it);
 
-          /* We moved the window start towards BEGV, so PT may be now
-             in the scroll margin at the bottom.  */
-          move_it_to (&it, PT, -1,
-                      it.last_visible_y - this_scroll_margin - 1, -1,
-                      MOVE_TO_POS | MOVE_TO_Y);
+      /* We moved the window start towards BEGV, so PT may be now
+         in the scroll margin at the bottom.  */
+      move_it_to (&it, PT, -1,
+                  it.last_visible_y - this_scroll_margin - 1, -1,
+                  MOVE_TO_POS | MOVE_TO_Y);
+
+      if (IT_CHARPOS (it) == PT)
+        /* We found PT before we found the display margin, so PT is ok.  */
+        ;
+      else if (preserve_y >= 0)
+        {
+          SET_TEXT_POS_FROM_MARKER (start, w->start);
+          start_display (&it, w, start);
+          /* If we have a header line, take account of it.  */
+          if (WINDOW_WANTS_HEADER_LINE_P (w))
+            preserve_y -= CURRENT_HEADER_LINE_HEIGHT (w);
 
+          move_it_to (&it, -1, -1, preserve_y, -1, MOVE_TO_Y);
+          SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
+        }
+      else
+        {
           /* Save our position, in case it's correct.  */
           charpos = IT_CHARPOS (it);
           bytepos = IT_BYTEPOS (it);
 
           /* See if point is on a partially visible line at the end.  */
           move_it_by_lines (&it, 1, 1);
+
           if (it.current_y > it.last_visible_y)
             /* The last line was only partially visible, so back up two
                lines to make sure we're on a fully visible line.  */
@@ -6755,7 +6779,9 @@ If there is only one window, it is split regardless of this value.  */);
 
   DEFVAR_LISP ("scroll-preserve-screen-position",
                &Vscroll_preserve_screen_position,
-               doc: /* *Non-nil means scroll commands move point to keep its screen line unchanged.  */);
+               doc: /* *Non-nil means scroll commands move point to keep its screen line unchanged.
+This is only when it is impossible to keep point fixed and still
+scroll as specified.  */);
   Vscroll_preserve_screen_position = Qnil;
 
   DEFVAR_LISP ("window-configuration-change-hook",