abstract class CustomControl : UserControl
{
protected abstract int DoStuff();
}
class DetailControl : CustomControl
{
protected override int DoStuff()
You can use a TypeDescriptionProviderAttribute to provide a concrete design-time implementation for your abstract base class. See http://wonkitect.wordpress.com/2008/06/20/using-visual-studio-whidbey-to-design-abstract-forms/ for details.