Avoid crashes when deleting owned top level windows.

Don't delay the TLW destruction if it has a parent and its parent is already
being deleted: we can't delay the inevitable in this case and only succeed in
making the program crash if we try.

Closes #15743.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75447 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/toplvcmn.cpp

@@ -101,6 +101,16 @@ wxTopLevelWindowBase::~wxTopLevelWindowBase()
 
 bool wxTopLevelWindowBase::Destroy()
 {
+    // We can't delay the destruction if our parent is being already destroyed
+    // as we will be deleted anyhow during its destruction and the pointer
+    // stored in wxPendingDelete would become invalid, so just delete ourselves
+    // immediately in this case.
+    if ( wxWindow* parent = GetParent() )
+    {
+        if ( parent->IsBeingDeleted() )
+            return wxNonOwnedWindow::Destroy();
+    }
+
     // delayed destruction: the frame will be deleted during the next idle
     // loop iteration
     if ( !wxPendingDelete.Member(this) )