Returns data that has been stored on this menu.
        
        :param      key     | <str>
                    default | <variant>
        
        :return     <variant>

def customData( self, key, default = None ):
        """
        Returns data that has been stored on this menu.
        
        :param      key     | <str>
                    default | <variant>
        
        :return     <variant>
        """
        key     = nativestring(key)
        menu    = self
        while (not key in menu._customData and \
               isinstance(menu.parent(), XMenu)):
            menu = menu.parent()
        
        return menu._customData.get(nativestring(key), default)