Fix bug #11653 with cursor positioning in a row that has only strings.

 src/xdisp.c (set_cursor_from_row): Don't dereference glyphs_end.  If
 all the glyphs of the glyph row came from strings, and we have no
 cursor positioning clues, put the cursor on the first glyph of the
 row.

2 files changed, 23 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index b5a22a0ebce..3138bea28fa 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2012-06-16  Eli Zaretskii  <eliz@gnu.org>
+
+        * xdisp.c (set_cursor_from_row): Don't dereference glyphs_end.  If
+        all the glyphs of the glyph row came from strings, and we have no
+        cursor positioning clues, put the cursor on the first glyph of the
+        row.  (Bug#11653)
+
 2012-06-16  Andreas Schwab  <schwab@linux-m68k.org>
 
         * category.h (CHAR_HAS_CATEGORY): Define as inline.
diff --git a/src/xdisp.c b/src/xdisp.c
index 0eae25de54a..e09116fe0ca 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -14260,6 +14260,7 @@ set_cursor_from_row (struct window *w, struct glyph_row *row,
              the cursor is not on this line.  */
           if (cursor == NULL
               && (row->reversed_p ? glyph <= end : glyph >= end)
+              && (row->reversed_p ? end > glyphs_end : end < glyphs_end)
               && STRINGP (end->object)
               && row->continued_p)
             return 0;
@@ -14289,6 +14290,21 @@ set_cursor_from_row (struct window *w, struct glyph_row *row,
  compute_x:
   if (cursor != NULL)
     glyph = cursor;
+  else if (glyph == glyphs_end
+           && pos_before == pos_after
+           && STRINGP ((row->reversed_p
+                        ? row->glyphs[TEXT_AREA] + row->used[TEXT_AREA] - 1
+                        : row->glyphs[TEXT_AREA])->object))
+    {
+      /* If all the glyphs of this row came from strings, put the
+         cursor on the first glyph of the row.  This avoids having the
+         cursor outside of the text area in this very rare and hard
+         use case.  */
+      glyph =
+        row->reversed_p
+        ? row->glyphs[TEXT_AREA] + row->used[TEXT_AREA] - 1
+        : row->glyphs[TEXT_AREA];
+    }
   if (x < 0)
     {
       struct glyph *g;