DropShadow is an extender which applies a "Drop Shadow" to a Panel. It allows you to specify
how wide the shadow is as well as how opaque it is, or if you would like rounded corners.
For pages that allow the user to move or resize the panel, the DropShadow has a mode that
will resize/reposition it to match that of the target panel at run time.
The control above is initialized with this code. The properties in italic are optional.
<ajaxToolkit:DropShadowExtender ID="dse" runat="server"