From 746956a6aeb8e4de3134493b17b3f45af9a48c73 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Thu, 29 Oct 2015 07:42:05 -0400
Subject: [PATCH] skip clean-up of bitmap that isn't there

Backing-bitmap allocation might fail for a too-large window?
---
 gui-lib/mred/private/wx/common/backing-dc.rkt | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/gui-lib/mred/private/wx/common/backing-dc.rkt b/gui-lib/mred/private/wx/common/backing-dc.rkt
index 2724a9f5..3cda0c7d 100644
--- a/gui-lib/mred/private/wx/common/backing-dc.rkt
+++ b/gui-lib/mred/private/wx/common/backing-dc.rkt
@@ -96,8 +96,9 @@
             (set! retained-cr #f)
             (internal-set-bitmap #f #t)
             (super release-cr retained-cr)
-            (proc bm)
-            (release-backing-bitmap bm)))))
+            (when bm
+              (proc bm)
+              (release-backing-bitmap bm))))))
 
     (define/public (start-backing-retained)
       (as-entry