Designers and Abstract Classes

Just ran into this today: Designers and Abstract Classes.

This sucks. I had a nice abstract class implementing an interface to force child forms to implement the interface - now I can't to that in any elegant fashion. Do I implement the interface on the base class and provide empty virtual method implementations, thereby ensuring that the interface is followed - but not that a true implementation is completed - or do I just hope that the child controls will implement the interface?