Fix bug #8468 with redisplay when scroll-margin > 0.

 src/xdisp.c (redisplay_window): Don't try to determine the character
 position of the scroll margin if the window start point w->startp
 is outside the buffer's accessible region.

2 files changed, 14 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 6e9a169e8a8..c164c6b5f58 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2011-04-11  Eli Zaretskii  <eliz@gnu.org>
+
+        * xdisp.c (redisplay_window): Don't try to determine the character
+        position of the scroll margin if the window start point w->startp
+        is outside the buffer's accessible region.
+
 2011-03-30  Eli Zaretskii  <eliz@gnu.org>
 
         * xdisp.c (syms_of_xdisp) <scroll-conservatively>: Document the
diff --git a/src/xdisp.c b/src/xdisp.c
index 9e331739cd9..2b032bd6597 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -14248,7 +14248,14 @@ redisplay_window (Lisp_Object window, int just_this_one_p)
 
       /* If there is a scroll margin at the top of the window, find
          its character position.  */
-      if (margin)
+      if (margin
+          /* Cannot call start_display if startp is not in the
+             accessible region of the buffer.  This can happen when we
+             have just switched to a different buffer and/or changed
+             its restriction.  In that case, startp is initialized to
+             the character position 1 (BEG) because we did not yet
+             have chance to display the buffer even once.  */
+          && BEGV <= CHARPOS (startp) && CHARPOS (startp) <= ZV)
         {
           struct it it1;