From 86c1fe4c7956e935695fb00130ab6e35788443be Mon Sep 17 00:00:00 2001
From: Stefan Csomor <csomor@advancedconcepts.ch>
Date: Tue, 5 Jan 2021 15:35:48 +0100
Subject: [PATCH] Fixing crash under BigSur

We get a late redraw event in the current 11.X versions, fixes #19030
---
 src/osx/cocoa/window.mm | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/osx/cocoa/window.mm b/src/osx/cocoa/window.mm
index bd249c3e3c..bca8dc1a13 100644
--- a/src/osx/cocoa/window.mm
+++ b/src/osx/cocoa/window.mm
@@ -2310,6 +2310,9 @@ void wxWidgetCocoaImpl::drawRect(void* rect, WXWidget slf, void *WXUNUSED(_cmd))
     // Restrict the update region to the shape of the window, if any, and also
     // remember the region that we need to clear later.
     wxNonOwnedWindow* const tlwParent = wxpeer->MacGetTopLevelWindow();
+    if ( tlwParent == NULL )
+        return;
+    
     const bool isTopLevel = tlwParent == wxpeer;
     wxRegion clearRgn;
     if ( tlwParent->GetWindowStyle() & wxFRAME_SHAPED )