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