• Page Web :

<form id="form1" runat="server">

    <asp:ScriptManager ID="ScriptManager1" runat="server" />

    <asp:UpdatePanel ID="updPnl" runat="server">

        <ContentTemplate>

            <div style="text-align: center;">

                <asp:Button runat="server"

ID="btn1"

Text="click me"

OnClick="btn1_Click" />

                <br />

                <asp:TextBox runat="server"

ID="txt1">

    </asp:TextBox>

                <asp:UpdateProgress ID="updProg"

runat="server">

                <ProgressTemplate>

                   <div style="text-align: center;

background-color: Gray; top: 0px;

bottom: 0px; position: absolute;

                        right: 0px; left: 0px;

-moz-opacity: 0.5; opacity: 0.5;

filter: alpha(opacity=50);">

                   </div>

                   <div style="margin-top: 25%; text-align: center;">

                     <img alt="Loading..." src="images/ajax-loader_blue.gif" />

   <br />

                     <span>LOADING...</span>

                   </div>

                 </ProgressTemplate>

                </asp:UpdateProgress>

            </div>

        </ContentTemplate>

    </asp:UpdatePanel>

    </form>

• Code Behind

(ici la simulation d'une longue attente :)

protected void btn1_Click(object sender, EventArgs e)

{

System.Threading.Thread.Sleep(5000);

txt1.Text = "test";

}

Pour télécharger l'image ajaxLoader : http://ajaxload.info/