Kevin,

>I pulled down the sample from MSDN, which didn't compile. But I looked at the code, as well as sample code from some other sites - and I'm really missing something. Obviously there's something going on behind the scenes with the control designers...but I just don't see how I can implement something to add properties that a control designer can see.

Try this...here's someone else who has used the extender provider to enhance menus...hopefully his sample code will run for you:

http://www.codeproject.com/cs/menu/MenuExtender.asp

Regards,