wxMenu::Insert() seems to work, bug in wxMenuBase::Insert() is corrected

(inserting an item at pos == GetCount() should be the same as appending and
not an error)


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@4818 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/menu.h

@@ -99,6 +99,9 @@ private:
     // common code for all constructors:
     void Init();
 
+    // common part of Append and Insert
+    bool GtkAppend(wxMenuItem *item);
+
     DECLARE_DYNAMIC_CLASS(wxMenu)
 };