1 files changed, 47 insertions, 17 deletions

diff --git a/src/window.c b/src/window.c
index bb414e7d311..4aeb8b39a70 100644
--- a/src/window.c
+++ b/src/window.c
@@ -4979,27 +4979,34 @@ window_scroll_pixel_based (Lisp_Object window, int n, bool whole, bool noerror)
 
   if (n > 0)
     {
+      int last_y = it.last_visible_y - this_scroll_margin - 1;
+
       /* 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
+      if (IT_CHARPOS (it) == PT
+          && it.current_y >= this_scroll_margin
+          && it.current_y <= last_y - WINDOW_HEADER_LINE_HEIGHT (w)
           && (NILP (Vscroll_preserve_screen_position)
               || EQ (Vscroll_preserve_screen_position, Qt)))
         /* We found PT at a legitimate height.  Leave it alone.  */
         ;
-      else if (window_scroll_pixel_based_preserve_y >= 0)
-        {
-          /* If we have a header line, take account of it.
-             This is necessary because we set it.current_y to 0, above.  */
-          move_it_to (&it, -1,
-                      window_scroll_pixel_based_preserve_x,
-                      (window_scroll_pixel_based_preserve_y
-                       - WINDOW_WANTS_HEADER_LINE_P (w)),
-                      -1, MOVE_TO_Y | MOVE_TO_X);
-          SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
-        }
       else
         {
+          if (window_scroll_pixel_based_preserve_y >= 0)
+            {
+              /* Don't enter the scroll margin at the end of the window.  */
+              int goal_y = min (last_y, window_scroll_pixel_based_preserve_y);
+
+              /* If we have a header line, take account of it.  This
+                 is necessary because we set it.current_y to 0, above.  */
+              move_it_to (&it, -1,
+                          window_scroll_pixel_based_preserve_x,
+                          goal_y - WINDOW_HEADER_LINE_HEIGHT (w),
+                          -1, MOVE_TO_Y | MOVE_TO_X);
+            }
+
+          /* Get out of the scroll margin at the top of the window.  */
           while (it.current_y < this_scroll_margin)
             {
               int prev = it.current_y;
@@ -5023,7 +5030,7 @@ window_scroll_pixel_based (Lisp_Object window, int n, bool whole, bool noerror)
       /* 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 - CURRENT_HEADER_LINE_HEIGHT (w)
+                  (it.last_visible_y - WINDOW_HEADER_LINE_HEIGHT (w)
                    - this_scroll_margin - 1),
                   -1,
                   MOVE_TO_POS | MOVE_TO_Y);
@@ -5074,14 +5081,20 @@ window_scroll_pixel_based (Lisp_Object window, int n, bool whole, bool noerror)
         ;
       else if (window_scroll_pixel_based_preserve_y >= 0)
         {
+          int goal_y = min (it.last_visible_y - this_scroll_margin - 1,
+                            window_scroll_pixel_based_preserve_y);
+
+          /* Don't let the preserved screen Y coordinate put us inside
+             any of the two margins.  */
+          if (goal_y < this_scroll_margin)
+            goal_y = this_scroll_margin;
           SET_TEXT_POS_FROM_MARKER (start, w->start);
           start_display (&it, w, start);
           /* It would be wrong to subtract CURRENT_HEADER_LINE_HEIGHT
              here because we called start_display again and did not
              alter it.current_y this time.  */
           move_it_to (&it, -1, window_scroll_pixel_based_preserve_x,
-                      window_scroll_pixel_based_preserve_y, -1,
-                      MOVE_TO_Y | MOVE_TO_X);
+                      goal_y, -1, MOVE_TO_Y | MOVE_TO_X);
           SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
         }
       else
@@ -5197,6 +5210,7 @@ window_scroll_line_based (Lisp_Object window, int n, bool whole, bool noerror)
       w->force_start = true;
 
       if (!NILP (Vscroll_preserve_screen_position)
+          && this_scroll_margin == 0
           && (whole || !EQ (Vscroll_preserve_screen_position, Qt)))
         {
           SET_PT_BOTH (pos, pos_byte);
@@ -5222,8 +5236,16 @@ window_scroll_line_based (Lisp_Object window, int n, bool whole, bool noerror)
                          marker_byte_position (opoint_marker));
           else if (!NILP (Vscroll_preserve_screen_position))
             {
+              int nlines = window_scroll_preserve_vpos;
+
               SET_PT_BOTH (pos, pos_byte);
-              Fvertical_motion (original_pos, window, Qnil);
+              if (window_scroll_preserve_vpos < this_scroll_margin)
+                nlines = this_scroll_margin;
+              else if (window_scroll_preserve_vpos
+                       >= w->total_lines - this_scroll_margin)
+                nlines = w->total_lines - this_scroll_margin - 1;
+              Fvertical_motion (Fcons (make_number (window_scroll_preserve_hpos),
+                                       make_number (nlines)), window, Qnil);
             }
           else
             SET_PT (top_margin);
@@ -5249,8 +5271,16 @@ window_scroll_line_based (Lisp_Object window, int n, bool whole, bool noerror)
             {
               if (!NILP (Vscroll_preserve_screen_position))
                 {
+                  int nlines = window_scroll_preserve_vpos;
+
                   SET_PT_BOTH (pos, pos_byte);
-                  Fvertical_motion (original_pos, window, Qnil);
+                  if (window_scroll_preserve_vpos < this_scroll_margin)
+                    nlines = this_scroll_margin;
+                  else if (window_scroll_preserve_vpos
+                           >= ht - this_scroll_margin)
+                    nlines = ht - this_scroll_margin - 1;
+                  Fvertical_motion (Fcons (make_number (window_scroll_preserve_hpos),
+                                           make_number (nlines)), window, Qnil);
                 }
               else
                 Fvertical_motion (make_number (-1), window, Qnil);