code: def _update_proxy(self, change):
          
          if change['type'] == 'event':
              name = 'do_'+change['name']
              if hasattr(self.proxy, name):
                  handler = getattr(self.proxy, name)
                  handler()
          else:
              super(WebView, self)._update_proxy(change)
docs: An observer which sends the state change to the proxy.