From 5b130f274edba5827fa68523def9e631824be5b8 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Fri, 16 Dec 2011 19:47:55 +0000
Subject: [PATCH] Corrected test for region validity in wxMSW
 wxRegion::DoOffset().

Checking M_REGION is not enough as the region can be invalid (meaning
m_refData dereferenced inside M_REGION is NULL itself) and not just not
initialized, so it resulted in crashes and not just the expected assert
failure when wxRegion::Offset() was called for an invalid region.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70017 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/msw/region.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/msw/region.cpp b/src/msw/region.cpp
index fed4cda96b..fece55e9c5 100644
--- a/src/msw/region.cpp
+++ b/src/msw/region.cpp
@@ -165,7 +165,8 @@ void wxRegion::Clear()
 
 bool wxRegion::DoOffset(wxCoord x, wxCoord y)
 {
-    wxCHECK_MSG( M_REGION, false, wxT("invalid wxRegion") );
+    const HRGN hrgn = GetHrgn();
+    wxCHECK_MSG( hrgn, false, wxT("invalid wxRegion") );
 
     if ( !x && !y )
     {
@@ -175,7 +176,7 @@ bool wxRegion::DoOffset(wxCoord x, wxCoord y)
 
     AllocExclusive();
 
-    if ( ::OffsetRgn(GetHrgn(), x, y) == ERROR )
+    if ( ::OffsetRgn(hrgn, x, y) == ERROR )
     {
         wxLogLastError(wxT("OffsetRgn"));