Collapsible Panel Extender in ASP.NET

Collapsible Panel Extender


In this article, I will show you step by step procedure, how to use a Collapsible Panel Extender

 In ASP.NET using Visual Studio 2005 or Visual Studio 2008.

To follow this code sample, you must use Visual Studio 2005 or Visual Studio 2008.

I have used <! –    –> to comment HTML part of the code.

Collapsible Panel Extender is a part of AjaxControlToolkit.
To attach right click on the toolbox under Ajax Extensions and select Choose Items - > Browse Button - > select the AjaxControlToolkit.dll. If you are using Visual Studio 2008, you may not need AJAX Toolkit but if you are using Visual Studio 2005, you will need to download it from or

Step 1. Start -> All Programs -> Visual Studio 2005 or Visual Studio 2008

Step 2. Now go to File Menu -> New -> Web Site

Step 3. 

Under Visual Studio Installed Template-> Choose ASP.NET WEB SITE -> Choose File System from the location combo box -> Set the path by the browse button - > Choose the language from the Language ComboBox (Visual C# , Visual Basic , J #)

Choose Visual C#

Step 4. Click on the OK Button.

This is the source code window and in this page you will se this code.


<%@ Page Language=”C#” AutoEventWireup=”true”  CodeFile=”Default.aspx.cs” Inherits=”_Default” %>


<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “”>


<html xmlns=””>

<head runat=”server”>

<title>Type your webpage title here</title>  <!– Here you can specify your page title in between title tag ->



<form id=”form1? runat=”server”>



<!– In between div tags you can manage your web controls like buttons, labels, picture Box, ImageMap etc –>







See here is a tab named Design in the bottom of this page.
Step 5. Click on this tab and you will see a blank web page where you can drag any control from the toolbox (which is in the left side of this window).

Step 6. Now drag some controls under the AJAX Extensions.

First control you are going to drag and drop on the page is - Script Manager.

first add a tag on the top of your source code window:

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

Under the form tag,

Don’t be frustrate on seeing this code please read carefully it’s very simple.


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


    <asp:LinkButton ID ="linkbutton1" runat="server" >

    About AJAX...



    <asp:Label ID ="label1" runat="server" ></asp:Label>


    <asp:Panel ID ="Panel1" runat="server" BackColor="LightPink" ForeColor="DarkSalmon" Font-Bold="true">


Microsoft has a complicated relationship with Ajax. On the one hand, the company wants

to provide its existing ASP.NET developers with an easy way to implement Ajax functionality

without having to learn JavaScript. On the other hand, Microsoft recognizes that the

future is on the client. Therefore, it wants to provide web developers with the tools they

need to build pure client-side Ajax applications. For these reasons, Microsoft has both a

server-side Ajax framework and a client-side Ajax framework.

If you want to retrofit an existing ASP.NET application to take advantage of Ajax, you can

take advantage of Microsoft’s server-side Ajax framework. To take advantage of the serverside

framework, you don’t need to write a single line of JavaScript code. You can continue

to build ASP.NET pages with server-side controls in the standard way. You learn how to

take advantage of the server-side Ajax framework in this chapter.

The advantage of the server-side framework is that it provides existing ASP.NET developers

with a painless method of doing Ajax. The disadvantage of the server-side framework is

that it doesn’t escape all the problems associated with a server-side framework. You still

have to run back to the server whenever you perform any client-side action.


        <cc1:CollapsiblePanelExtender ID="CollapsiblePanelExtender1" runat="server" CollapseControlID="linkbutton1" ExpandControlID="linkbutton1" CollapsedSize="0" CollapsedText="Expand it..." ExpandDirection="Vertical" ExpandedSize="250" ExpandedText="Colaspe it..." SuppressPostBack="true" TargetControlID="Panel1" TextLabelID="label1">



Step 7. Now run your web site by Ctrl + F5

Step 8. When you run the Collapsible Panel Extender will seem like this...

 Collaspible extender contorl.JPG

When you click on the “About AJAX “it will expand and when you click on the “About AJAX” again it will

Collapse again…

Step 9. Close Browser


Step 10. Close Visual Studio…



--Nikhil Kumar


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