Default.aspx

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
    CodeBehind="Default.aspx.cs" Inherits="Testing._Default" %>

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc2" %>

<%@ Register Assembly="Testing" Namespace="Testing" TagPrefix="cc1" %>

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<style type="text/css">
            .PnlDesign
            {
                border: solid 1px #000000;
                height: 250px;
                width: 330px;
                overflow-y: scroll;
                background-color: #EAEAEA;
                font-size: 15px;
                font-family: Arial;
            }
            .txtboxaschkbox
            {
                background-image: url(../Images/drpdwn.png);
                width: 300px;
                background-position: right top;
                background-repeat: no-repeat;
                cursor: pointer;
                cursor: hand;
            }
        </style>
<fieldset>
            <legend>Role</legend>
            <table width="500">
                <tr>
                <td>A</td>
                    <td valign="top">
                        <asp:DropDownList ID="Roles" runat="server" AutoPostBack="True" OnSelectedIndexChanged="roles_SelectedIndexChanged">
                        </asp:DropDownList>
                    </td>
                    <td valign="top">
                        <asp:UpdatePanel ID="UpdatePanel" runat="server">
                            <ContentTemplate>
                                <asp:TextBox ID="txtAuthority" Text="Authorities" runat="server" CssClass="txtboxaschkbox" Visible="false"></asp:TextBox>
                                <asp:Panel runat="server" ID="PnlAuth" Visible="false" CssClass="PnlDesign">
                                    <cc1:EnhancedCheckboxList ID="Authorities" runat="server">
                                    </cc1:EnhancedCheckboxList>
                                </asp:Panel>
                                <cc2:PopupControlExtender runat="server" ID="PceSelectAuthority" TargetControlID="txtAuthority"
                                    PopupControlID="PnlAuth" Position="Bottom"/>
                            </ContentTemplate>
                            <Triggers>
                                <asp:AsyncPostBackTrigger ControlID="Roles" />
                            </Triggers>
                        </asp:UpdatePanel>
                    </td>
                </tr>
                <tr>
                <td>B</td>
                    <td valign="top">
                        <asp:DropDownList ID="Roles2" runat="server" AutoPostBack="True" OnSelectedIndexChanged="roles2_SelectedIndexChanged">
                        </asp:DropDownList>
                    </td>
                    <td valign="top">
                        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                            <ContentTemplate>
                                <asp:TextBox ID="txtAuthority2" Text="Authorities" runat="server" CssClass="txtboxaschkbox" Visible="false"></asp:TextBox>
                                <asp:Panel runat="server" ID="PnlAuth2" Visible="false" CssClass="PnlDesign">
                                    <cc1:EnhancedCheckboxList ID="Authorities2" runat="server">
                                    </cc1:EnhancedCheckboxList>
                                </asp:Panel>
                                <cc2:PopupControlExtender runat="server" ID="PceSelectAuthority2" TargetControlID="txtAuthority2"
                                    PopupControlID="PnlAuth2" Position="Bottom"/>
                            </ContentTemplate>
                            <Triggers>
                                <asp:AsyncPostBackTrigger ControlID="Roles2" />
                            </Triggers>
                        </asp:UpdatePanel>
                    </td>
                </tr>
            </table>

        </fieldset>

                <asp:Button ID="Button1" runat="server" Text="Button"
                onclick="Button1_Click" />
</asp:Content>