No real changes, just add a wxCHECK to GetDlgUnitBase().

Verify that we do have a valid TLW parent: even though this normally should be
always the case, it might not be when the window is being created or destroyed,
see #14355.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71731 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/wincmn.cpp

@@ -2747,6 +2747,8 @@ wxSize wxWindowBase::GetDlgUnitBase() const
 {
     const wxWindowBase * const parent = wxGetTopLevelParent((wxWindow*)this);
 
+    wxCHECK_MSG( parent, wxDefaultSize, wxS("Must have TLW parent") );
+
     if ( !parent->m_font.IsOk() )
     {
         // Default GUI font is used. This is the most common case, so