Custom widgets

[Whiplash]

I want to build some basic kid games for Linux (Ubuntu/EdUbuntu) and
so after looking around I've decided that Python would probably be the
path of least resistance.

I have a need to create custom gui elements (widgets?). I want these
games to be very graphical. Not 3d or anything crazy, I just want them
to look fun and so the buttons and things will all need to be custom.
For instance, I might have spaceship or alien shaped buttons and the
background of my window might be a photo of a galaxy. Make sense?

So I've started looking at Tkinter, and PyGTK but I don't want to get
too deep without knowing if they'll work for me. Do either of these
toolkits provide the ability to create custom widgets? Is there
something else I should be looking at instead? I'm not concerned with
cross platform compatibility, I just want to use something that will
be readily available in your average Ubuntu install.

Thanks!

Dana