def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def draw(self, context):
        props = self.layout.operator("wm.context_set_value", text="Blender (default)")
        props.data_path = "window_manager.keyconfigs.active"
        props.value = "context.window_manager.keyconfigs.default"

        # now draw the presets
        Menu.draw_preset(self, context)