ASP.NET - UpdatePanelProgressExtender

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page 
{


    protected void updateButton1_Click(object sender, EventArgs e)
    {
        System.Threading.Thread.Sleep(2000);
    }

    protected void updateButton2_Click(object sender, EventArgs e)
    {
        System.Threading.Thread.Sleep(2000);
    }

    protected void externalUpdateButton1_Click(object sender, EventArgs e)
    {
        System.Threading.Thread.Sleep(2000);
    }
}