DropDown is an ASP.NET AJAX extender that can be attached to almost any ASP.NET control to provide
a SharePoint-style drop-down menu. The displayed menu is merely another panel or control. In the
above sample the drop-down is a Panel which contains LinkButtons. The drop-down is activated by left-
or right-clicking the attached control. If the behavior is attached to a Hyperlink or LinkButton,
clicking on the link itself will operate normally.
The control above is initialized with this code. The italic properties
<ajaxToolkit:DropDownExtender runat="server" ID="DDE"