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.  */