code: function(oEvent) {
  			var sEventId = oEvent.getParameter("EventId");
  
  			if (sEventId === "messageSelected") {
  				if (oEvent.getParameter("type") === "listenerAttached") {
  					this._bEnableMessageSelect = true;
  				} else if (oEvent.getParameter("type") === "listenerDetached") {
  					this._bEnableMessageSelect = false;
  				}
  
  				this.fireEvent("_enableMessageSelect", {
  					enabled : this._bEnableMessageSelect,
  					notifier : this
  				});
  			}
  		}
docs: Checks if the 'messageSelected' event was attached to the Notifier. If so
  the corresponding event is fired and e.g. the NotificationBar can react
  on that.