Creates the 'menu' - implemented as a button which opens a
        pop-up menu since wxPython does not allow a menu as a control

def _create_menu(self):
        """
        Creates the 'menu' - implemented as a button which opens a
        pop-up menu since wxPython does not allow a menu as a control
        """
        DEBUG_MSG("_create_menu()", 1, self)
        self._menu = MenuButtonWx(self)
        self.AddControl(self._menu)
        self.AddSeparator()