<asp:UpdatePanel ID="upnl" runat="server">
<ContentTemplate>
<asp:CheckBox ID="chk1" runat="server" AutoPostBack='true' Text="check test" OnCheckedChanged="chk1_OnCheckedChanged"/>
<asp:Button ID="Button1" runat="server" Text="btn1"/>
</ContentTemplate>
</asp:UpdatePanel>
<div id="divHide">
<asp:UpdateProgress ID="upnldd" runat="server" DisplayAfter="1" AssociatedUpdatePanelID="upnl">
<ProgressTemplate>
Loading....
</ProgressTemplate>
</asp:UpdateProgress>
</div>
</div>
<script type="text/javascript">
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_beginRequest(BeginRequestHandler);
function BeginRequestHandler(sender, args) {
if (args._postBackElement.id != '<%=Button1.ClientID %>')
document.getElementById('divHide').style.display = "none";
else
document.getElementById('divHide').style.display = "block";
}
</script>