If I remember correctly, easygui is just a bunch of tkinter based dialog boxes. As a GUI toolkit it is BS to say it politely. Spend some time learning tkinter, it is a pretty powerful GUI toolkit, and you get used to GUI design and thinking.
More advanced is PyQT or PySide, but it will bring along quite a steep learning curve. PyGTK is rather difficult to install in the Windows OS world, and it is, along with wxPython, not yet available for the Python3 (could change soon).