How to use image in UpdateProgress in asp.net ajax

Image in UpdateProgress
UsingUpdateProgressImage.aspx

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Drawing" %>

<!DOCTYPE html>

<script runat="server">
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            CheckBoxList1.ForeColor = Color.SeaGreen;
            CheckBoxList1.BackColor = Color.LawnGreen;
            CheckBoxList1.Font.Bold = true;
            CheckBoxList1.Font.Size = FontUnit.Medium;
            CheckBoxList1.BorderColor = Color.MediumSeaGreen;
            CheckBoxList1.BorderWidth = 1;
            CheckBoxList1.Width = 450;
            CheckBoxList1.RepeatColumns = 2;
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        System.Threading.Thread.Sleep(5000);
        CheckBoxList1.Items.Add(DateTime.Now.ToLongTimeString());
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Ajax UpdateProgress image - How to use image in UpdateProgress in asp.net ajax</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:Crimson; font-style:italic;">Ajax UpdateProgress Example: Using Image</h2>
        <hr width="450" align="left" color="LightPink" />
        <asp:ScriptManager 
            ID="ScriptManager1"
            runat="server"
            >
        </asp:ScriptManager>
        <asp:UpdateProgress ID="UpdateProgress1" runat="server">
            <ProgressTemplate>
                <asp:Panel 
                    ID="Pnael1"
                    runat="server"
                    Width="450"
                    HorizontalAlign="Center"
                    >
                    <asp:Image 
                        ID="Image1"
                        runat="server"
                        ImageUrl="~/Images/ProgressImage.gif"
                        />
                </asp:Panel>
            </ProgressTemplate>
        </asp:UpdateProgress>
        <br />
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:CheckBoxList 
                    ID="CheckBoxList1"
                    runat="server"
                    >
                </asp:CheckBoxList>
                <br /><br />
                <asp:Button 
                    ID="Button1" 
                    runat="server" 
                    OnClick="Button1_Click"
                    Font-Bold="true"
                    Height="45"
                    Text="Add Button Click Time In CheckBoxList"
                    ForeColor="DodgerBlue"
                    />
            </ContentTemplate>
        </asp:UpdatePanel>
    </div>
    </form>
</body>
</html>
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