Main window toolbar toggle event handler

def OnMainToolbarToggle(self, event):
        """Main window toolbar toggle event handler"""

        self.main_window.main_toolbar.SetGripperVisible(True)
        main_toolbar_info = \
            self.main_window._mgr.GetPane("main_window_toolbar")

        self._toggle_pane(main_toolbar_info)

        event.Skip()