return true from IsBeingDeleted() if any of the parent windows is marked for destruction too (see #9867)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@55570 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/wincmn.cpp

@@ -379,6 +379,12 @@ wxWindowBase::~wxWindowBase()
 #endif
 }
 
+bool wxWindowBase::IsBeingDeleted() const
+{
+    return m_isBeingDeleted ||
+            (!IsTopLevel() && m_parent && m_parent->IsBeingDeleted());
+}
+
 void wxWindowBase::SendDestroyEvent()
 {
     wxWindowDestroyEvent event;