//Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(beginReq);
//Sys.WebForms.PageRequestManager.getInstance().add_endRequest(endReq);
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_initializeRequest(beginReq);
prm.add_endRequest(endReq);
function beginReq(sender, args) {
    $find(ModalProgress).show();    
}

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