Fix bug #13055 with cursor positioning inside scroll-margin.

 src/xdisp.c (redisplay_window): If the cursor is visible, but inside
 the scroll margin, move point outside the margin.

2 files changed, 34 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index f2b65db257d..20ed5a99a1a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2012-12-03  Eli Zaretskii  <eliz@gnu.org>
+
+        * xdisp.c (redisplay_window): If the cursor is visible, but inside
+        the scroll margin, move point outside the margin.  (Bug#13055)
+
 2012-12-03  Jan Djärv  <jan.h.d@swipnet.se>
 
         * gtkutil.c (my_log_handler): New function.
diff --git a/src/xdisp.c b/src/xdisp.c
index 6199c2a436e..5f6d69dea3a 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -15717,6 +15717,35 @@ redisplay_window (Lisp_Object window, int just_this_one_p)
              Move it back to a fully-visible line.  */
           new_vpos = window_box_height (w);
         }
+      else if (w->cursor.vpos >=0)
+        {
+          /* Some people insist on not letting point enter the scroll
+             margin, even though this part handles windows that didn't
+             scroll at all.  */
+          struct frame *f = XFRAME (w->frame);
+          int margin = min (scroll_margin, WINDOW_TOTAL_LINES (w) / 4);
+          int pixel_margin = margin * FRAME_LINE_HEIGHT (f);
+          bool header_line = WINDOW_WANTS_HEADER_LINE_P (w);
+
+          /* Note: We add an extra FRAME_LINE_HEIGHT, because the loop
+             below, which finds the row to move point to, advances by
+             the Y coordinate of the _next_ row, see the definition of
+             MATRIX_ROW_BOTTOM_Y.  */
+          if (w->cursor.vpos < margin + header_line)
+            new_vpos
+              = pixel_margin + (header_line
+                                ? CURRENT_HEADER_LINE_HEIGHT (w)
+                                : 0) + FRAME_LINE_HEIGHT (f);
+          else
+            {
+              int window_height = window_box_height (w);
+
+              if (header_line)
+                window_height += CURRENT_HEADER_LINE_HEIGHT (w);
+              if (w->cursor.y >= window_height - pixel_margin)
+                new_vpos = window_height - pixel_margin;
+            }
+        }
 
       /* If we need to move point for either of the above reasons,
          now actually do it.  */