From 3d4b579bd8037d791c102fc0f5426a281aec6213 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Wed, 6 Feb 2008 19:58:30 +0000
Subject: [PATCH] correction after the previous commit which introduced bug
 1888014 [backport of r51574 from trunk]

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@51575 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/msw/button.cpp | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/msw/button.cpp b/src/msw/button.cpp
index 4a244235b0..e27bd01f84 100644
--- a/src/msw/button.cpp
+++ b/src/msw/button.cpp
@@ -357,26 +357,32 @@ void wxButton::SetDefault()
     SetDefaultStyle(this, true);
 }
 
-// special version of wxGetTopLevelParent() which is safe to call when the
-// parent is being destroyed: wxGetTopLevelParent() would just return NULL in
-// this case because wxWindow version of IsTopLevel() is used when it's called
-// during window destruction instead of wxTLW one, but we want to distinguish
-// between these cases
+// return the top level parent window if it's not being deleted yet, otherwise
+// return NULL
 static wxTopLevelWindow *GetTLWParentIfNotBeingDeleted(wxWindow *win)
 {
-    for ( ; win; win = win->GetParent() )
+    for ( ;; )
     {
-        if ( win->IsTopLevel() )
+        // IsTopLevel() will return false for a wxTLW being deleted, so we also
+        // need the parent test for this case
+        wxWindow * const parent = win->GetParent();
+        if ( !parent || win->IsTopLevel() )
         {
             if ( win->IsBeingDeleted() )
                 return NULL;
+
             break;
         }
+
+        win = parent;
     }
 
     wxASSERT_MSG( win, _T("button without top level parent?") );
 
-    return wxDynamicCast(win, wxTopLevelWindow);
+    wxTopLevelWindow * const tlw = wxDynamicCast(win, wxTopLevelWindow);
+    wxASSERT_MSG( tlw, _T("logic error in GetTLWParentIfNotBeingDeleted()") );
+
+    return tlw;
 }
 
 // set this button as being currently default