<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true"
    CodeFile="Default.aspx.cs" Inherits="_Default" Title="Untitled Page" %>

<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="Server">
    <telerik:radscriptblock id="RadScriptBlock1" runat="server">

        <script type="text/javascript">
window.onload =
function()
{
setTimeout(
 function(){
 window["<%= RadAjaxManager1.ClientID %>"].AjaxRequest("InitialPageLoad");
 }, 200);
}
</script>
    </telerik:radscriptblock>
    <telerik:radajaxmanager id="RadAjaxManager1" runat="server" onajaxrequest="RadAjaxManager1_AjaxRequest">
        <AjaxSettings>
            <telerik:AjaxSetting AjaxControlID="radAjaxManager1">
                <UpdatedControls>
                    <telerik:AjaxUpdatedControl ControlID="TabPanel" LoadingPanelID="AjaxLoadingPanel1" />
                </UpdatedControls>
            </telerik:AjaxSetting>
        </AjaxSettings>
    </telerik:radajaxmanager>
    few user controls go here
    <br />
    <asp:Button ID="Button1" runat="server" Text="POSTBACK" />
    <asp:Panel ID="TabPanel" runat="server">
        <asp:Panel ID="Panel2" Visible="false" runat="server">
            THIS IS WHAT I WANT TO SEE AFTER THE "InitialPageLoad" AJAX REQUEST</asp:Panel>
    </asp:Panel>
    <telerik:radajaxloadingpanel id="RadAjaxLoadingPanel1" runat="server" height="75px"
        width="75px">
        <img alt="Loading..." src='<%= RadAjaxLoadingPanel.GetWebResourceUrl(Page, "Telerik.Web.UI.Skins.Default.Ajax.loading.gif") %>' style="border: 0px;" />
    </telerik:radajaxloadingpanel>
</asp:Content>
