def on_event(self, event):
        """
        Process bokeh UIEvents adding timeout to process multiple concerted
        value change at once rather than firing off multiple plot updates.
        """
        self._queue.append((event))
        if not self._active and self.plot.document:
            self.plot.document.add_timeout_callback(self.process_on_event, 50)
            self._active = True