From 3c8787980c53da2afeafd1a7c09ff853aedb6b33 Mon Sep 17 00:00:00 2001
From: Ilya Lysenkov <lysenkov.ilya@gmail.com>
Date: Wed, 30 Jan 2013 15:26:49 +0400
Subject: [PATCH] Fixed cvDestroyAllWindows() without windows in QT (#2440)

---
 modules/highgui/src/window_QT.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/modules/highgui/src/window_QT.cpp b/modules/highgui/src/window_QT.cpp
index d617e71f9f..973b23c0c0 100644
--- a/modules/highgui/src/window_QT.cpp
+++ b/modules/highgui/src/window_QT.cpp
@@ -499,7 +499,7 @@ CV_IMPL void cvDestroyWindow(const char* name)
 CV_IMPL void cvDestroyAllWindows()
 {
     if (!guiMainThread)
-        CV_Error( CV_StsNullPtr, "NULL guiReceiver (please create a window)" );
+        return;
 
     QMetaObject::invokeMethod(guiMainThread,
         "destroyAllWindow",