code: func (ww *WidgetWatchers) PostEvent(wev EventWidget) {
  	for watcher := range ww.watchers {
  		// Deliver events to all listeners, ignoring return value.
  		watcher.HandleEvent(wev)
  	}
  }
docs: // PostEvent delivers the EventWidget to all registered watchers.  It is
  // to be called by the Widget implementation.