code: def _viewbox_set(self, viewbox):
          
          self._viewbox = viewbox
          # Connect
          viewbox.events.mouse_press.connect(self.viewbox_mouse_event)
          viewbox.events.mouse_release.connect(self.viewbox_mouse_event)
          viewbox.events.mouse_move.connect(self.viewbox_mouse_event)
          viewbox.events.mouse_wheel.connect(self.viewbox_mouse_event)
          viewbox.events.resize.connect(self.viewbox_resize_event)
docs: Friend method of viewbox to register itself.