If you want a component like the ImageList, however, that can interact with the designer, extend the Component class. Also, this has absolutely nothing to do with what kind of project you create. You are supposed to add classes to that and understand what's in the source file. A Windows Forms Application can contain all the same things a Windows Control Library can, and even an ASP.NET Web Application can, too, though a Windows Forms class won't do much good there. The difference is how the assemblies are built, whether they are self executing or loadable (among a few other differences in the PE/COFF header and where everything is located, etc.). Todd Davis wrote: Never code when it is past your bedtime... ...or before reading the documentation.
Microsoft MVP, Visual C# My Articles