[PyQt] Managing variables accross a multiple module GUI

[Oolongtea]

Yes that's what I'm trying to do with the program I'm cleaning up, since nearly everything was dumped in the main script and for the most part, in the mainwindow class. I'm trying to break down the program into what does the science, what does the IO, and then the GUI into basic functional blocs that can function independently (easier to test that way, isn't it?).
The challenge for me now is to figure out how to best structure the program from the variables point of view so each widget/class can do its thing.