DropDown is an ASP.NET AJAX extender that can be attached to almost any ASP.NET control. The extender can wrap any control to provide a SharePoint-style drop-down menu that is attached to the control. The menu that is displayed is merely another panel or control. In the above sample the drop-down is a Panel which contains an asp:Menu control. The drop-down is activated by left- or right-clicking the attached control. If the behavior is attached to an asp:Hyperlink or asp:LinkButton clicking on the link itself will operate normally.

The control above is initialized with this code. The italic properties are optional:

<ajaxToolkit:DropDownExtender runat="server" ID="DDE"
    TargetControlID="TextLabel" 
    DropDownControlID="DropPanel" />

• TargetControlID - The ID of the Control which will need a drop-down
• DropDownControlID - The ID of the Panel which will be displayed as the dropdown.