Fix assertion violations when clicking on Info bread-crumbs.

 src/xdisp.c (draw_glyphs): Don't draw in mouse face if mouse
 highlighting on the frame was cleared.  Prevents assertion
 violations when repeatedly clicking on the "Top" link of the
 "bread-crumbs" in Info buffers.

2 files changed, 10 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 8ca913b75fc..6c9893b2f4f 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2012-11-24  Eli Zaretskii  <eliz@gnu.org>
+
+        * xdisp.c (draw_glyphs): Don't draw in mouse face if mouse
+        highlighting on the frame was cleared.  Prevents assertion
+        violations when repeatedly clicking on the "Top" link of the
+        "bread-crumbs" in Info buffers.
+
 2012-11-23  Paul Eggert  <eggert@cs.ucla.edu>
             Eli Zaretskii  <eliz@gnu.org>
 
diff --git a/src/xdisp.c b/src/xdisp.c
index 4bb744a2f9d..8336594ca61 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -23512,7 +23512,9 @@ draw_glyphs (struct window *w, int x, struct glyph_row *row,
 
       /* If mouse highlighting is on, we may need to draw adjacent
          glyphs using mouse-face highlighting.  */
-      if (area == TEXT_AREA && row->mouse_face_p)
+      if (area == TEXT_AREA && row->mouse_face_p
+          && hlinfo->mouse_face_beg_row >= 0
+          && hlinfo->mouse_face_end_row >= 0)
         {
           struct glyph_row *mouse_beg_row, *mouse_end_row;