[metacity] core/boxes.c: fix unchecked values in meta_rectangle_clip_to_region()

[Thomas James Alexander Thurman <tthurman src gnome org>]

commit 5132ca4145b0f4f4afd5c4ddad6288bc56716140
Author: Sascha Silbe <sascha-org-sugar-git silbe org>
Date:   Wed Sep 23 17:48:27 2009 +0000

    core/boxes.c: fix unchecked values in meta_rectangle_clip_to_region()

 src/core/boxes.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/src/core/boxes.c b/src/core/boxes.c
index dda283a..e57663e 100644
--- a/src/core/boxes.c
+++ b/src/core/boxes.c
@@ -907,6 +907,9 @@ meta_rectangle_clip_to_region (const GList         *spanning_rects,
   const MetaRectangle *best_rect = NULL;
   int                  best_overlap = 0;
 
+  if (!rect)
+    return;
+
   /* First, find best rectangle from spanning_rects to which we will clip
    * rect into.
    */
@@ -933,7 +936,8 @@ meta_rectangle_clip_to_region (const GList         *spanning_rects,
         continue;
 
       /* Determine maximal overlap amount */
-      meta_rectangle_intersect (rect, compare_rect, &overlap);
+      if (!meta_rectangle_intersect (rect, compare_rect, &overlap))
+        continue;
       maximal_overlap_amount_for_compare = meta_rectangle_area (&overlap);
 
       /* See if this is the best rect so far */