make Set/GetLabel() set and return title in wxTLW, fixes #12371: Dialog::GetLabel() Inconsistent behaviour across operating systems

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65373 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/toplevel.h

@@ -72,6 +72,10 @@ public:
     virtual void SetTitle( const wxString &title );
     virtual wxString GetTitle() const { return m_title; }
 
+    virtual void SetLabel(const wxString& label) { SetTitle( label ); }
+    virtual wxString GetLabel() const            { return GetTitle(); }
+
+
     virtual bool SetTransparent(wxByte alpha);
     virtual bool CanSetTransparent();