Change storage of window menu label translation

Use member variable instead of global variable

include/wx/msw/mdi.h

@@ -85,6 +85,12 @@ public:
     virtual void RemoveMDIChild(wxMDIChildFrame *child);
 #endif // wxUSE_MENUS
 
+    // called by AddWindowMenu to remember the translation of the window menu label
+    void SetWindowMenuLabelTranslated();
+
+    // called by AddWindowMenu and RemoveWindowMenu to get the last used translation of the window menu label
+    const wxString GetWindowMenuLabelTranslated() const;
+
     // handlers
     // --------
 
@@ -150,6 +156,9 @@ private:
     // it was "handled", see OnActivate() and HandleActivate()
     bool m_activationNotHandled;
 
+    // holds the current translation for the window menu label
+    wxString m_windowMenuLabelTranslated;
+
 
     friend class WXDLLIMPEXP_FWD_CORE wxMDIChildFrame;