I guess that would be copy-and-paste inheritance.

>Dave,
>
>>>For example, you create a user control that contains three textboxes. Then you come up with the smart idea to subclass the textbox to create a mytextbox subclass. If you want your user control to contain three mytextboxes, you can't. You have to throw it away and create a new user control that contains three mytextboxes.<
>
>Hmmmmm ... I don't know why you say that. It's quite easy to do without throwing it away and recreating the UserControl, unless I'm misunderstanding what you're saying. All you have to do is edit your UserControl code and change all System.Windows.Forms.TextBox to MyTextbox instead. Unless you're talking about WebForms instead of WinForms, but even so couldn't you do a similar thing?
>
>~~Bonnie