def handle_scrollwheel(self, event):
        """Handle the scrollwheel (it is a ball on the mighty mouse)."""
        # relative Scrollwheel
        scroll_x, scroll_y = self._get_scroll(event)

        if scroll_x:
            self.events.append(
                self.emulate_wheel(scroll_x, 'x', self.timeval))

        if scroll_y:
            self.events.append(
                self.emulate_wheel(scroll_y, 'y', self.timeval))