/// <summary> /// Extends BeginInvoke so that when a state object is not needed, null does not need to be passed. /// <example> /// navigationfailedeventhandler.BeginInvoke(sender, e, callback); /// </example> /// </summary> public static IAsyncResult BeginInvoke(this NavigationFailedEventHandler navigationfailedeventhandler, Object sender, NavigationFailedEventArgs e, AsyncCallback callback) { if (navigationfailedeventhandler == null) { throw new ArgumentNullException("navigationfailedeventhandler"); } return(navigationfailedeventhandler.BeginInvoke(sender, e, callback, null)); }