GUI testing is a pain, with the tools I have tried so far. If you know of something like this let me know, and I'll stop reinventing the wheel! :)

GUITest is a GUI tester like what I really need:

Minimal integration needed: You shouldn't need to write your code thinking of using GUITester later on, just write it. Multiplatform, not X11 only or window only. Multi-widgetset (Gtk and Qt at least). Multi-language. Tests will be written in Python, but you should be able to write the app in C, Python or Eiffel.