Short story : use wxPython for your cross platform tools, it's awesome! Long story : our current character animation pipeline, how to say this, could use some optimization. So, to simplify some of the steps, I decided to write an animation editor for our own use, with the specific features we need. Artist uses Windows and I use Linux, so the choice was obvious : wxWidgets. Also, for ease of use and speed of development, I chose the Python wrapper, wxPython. I can't explain how pleased I am with wxPython. 2 days and a half, and 1400 lines of code later, I have an amazingly functional animation editor written from scratch. Chalk up another one for Python and one for wxWidgets!