MockGui
The way I do unittesting makes heavy use of monkeypatching, especially of subroutines called. For the GUI modules I made I noticed that I often used the same constructions in my test methods, being the mocking of methods of GUI classes. This motivated me to build something that I could import and reuse everywhere where applicable.
For convenience I just stuck everything for the same GUI toolkit into the same module and refrained from implementing the same type of inheritance as implemented in the originals. Currently they only contain whta I need for the tests that I have, so it's by no means an attempt to be complete. I do have modules for PyQT, WxPython and Tkinter available.