Thank you for that! I've never played with Gtk because I thought I remembered reading that it's sort of Unix-centric but you can get installed under Windows by jumping through multiple hoops.

On the other hand, the thought of rolling my own on a canvas and attaching an event to that never had occurred to me. I'd always seen Tk::NoteBook, and since it had tabs, just thought that would be the natural road to follow. Rather than trying to modify a module your third suggestion may be the easiest way to go.