|Think about Loose Coupling
I would probably go with Tk::Zinc myself, for the simple reason that it has scalable text, i.e. you can make the text objects zoom to size with the other items. The Tk canvas and Gnome2::Canvas can't do that, you need to switch fonts. Zinc also supports alpha layers so you can make cool buttons and effects.
I'm not really a human, but I play one on earth. Cogito ergo sum a bum