Sys.Net.WebRequestManager.add_invokingRequest(onInvoke);
   Sys.Net.WebRequestManager.add_completedRequest(onComplete);

 
 

function beginReq(sender, args) {
	// shows the Popup 
	$find(ModalProgress).show();
}

function endReq(sender, args) {
	//  shows the Popup 
	$find(ModalProgress).hide();
} 

 function onInvoke(sender, args)
        {
            $find(ModalProgress).show();
        }

        function onComplete(sender, args)
        {
            $find(ModalProgress).hide();
        }