Untitled

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <style type="text/css">

        .PnlDesign
        {
            border: solid 1px #000000;
            height: 150px;
            width: 330px;
            overflow-y:scroll;
            background-color: #EAEAEA;
            font-size: 15px;
            font-family: Arial;
        }
        .txtbox
        {
            background-image: url(../images/drpdwn.png);
            background-position: right top;
            background-repeat: no-repeat;
            cursor: pointer;
            cursor: hand;
        }
    </style>
</head>


    <body>
   <form id="Form1" runat="server">
 &nbsp;<asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <div>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
            <ContentTemplate>
                <asp:TextBox ID="txtCustomer" Text="Select Customers" runat="server" CssClass="txtbox"
                    Height="20px" Width="322px"></asp:TextBox>
                <asp:Panel ID="PnlCust" runat="server" CssClass="PnlDesign" style="text-align:left">
                    <asp:CheckBoxList ID="cblCustomerList" runat="server" AutoPostBack="true"
                        onselectedindexchanged="cblCustomerList_SelectedIndexChanged">
                        <asp:ListItem>Customer One</asp:ListItem>
                        <asp:ListItem>Customer Two</asp:ListItem>
                        <asp:ListItem>Customer Three</asp:ListItem>
                        <asp:ListItem>Customer Four</asp:ListItem>
                        <asp:ListItem>Customer Five</asp:ListItem>
                        <asp:ListItem>Customer Six</asp:ListItem>
                        <asp:ListItem>Customer Seven</asp:ListItem>
                    </asp:CheckBoxList>
                </asp:Panel>
                 <asp:Button ID="Button1" runat="server" Text="Reset" onclick="Button1_Click" />
                <br />
                <cc1:DropDownExtender ID="PceSelectCustomer" runat="server" TargetControlID="txtCustomer"
                    DropDownControlID="PnlCust" HighlightBorderColor="ActiveCaptionText">
                </cc1:DropDownExtender>

            </ContentTemplate>
        </asp:UpdatePanel>
    </div>

    </form>
</body>
</html>