有没有办法为某些异步回发禁用UpdateProgress？

<script type="text/javascript">    var prm = Sys.WebForms.PageRequestManager.getInstance();    prm.add_initializeRequest(InitializeRequest);    function InitializeRequest(sender, args) {        var updateProgress = $get('UpdateProgress1');        var postBackElement = args.get_postBackElement();        if (postBackElement.id == '<%= Button1.ClientID %>') { updateProgress.control._associatedUpdatePanelId = 'dummyId';        }        else{ updateProgress.control._associatedUpdatePanelId = null;        }    }</script>