Andrew,
I have worked rather closely with Python and Tkinter. It was a gross mess. In my very early days, I planned as my first VM hack to do a Tkinter extension. The big difficulty is that Squeak makes it very, very difficult to do callbacks, which are used extensively in Tkinter. My impression is that this is till a problem, even under FFI.
Andreas, your comments?
Callbacks are currently not support in the FFI stuff. There is more than one reason for it but for me the primary reason is that adding callbacks has some serious implications on the general working of the VM - so I was trying to avoid an (in my understanding unnecessary) complication for the forthcoming J3. My basic feeling about this is that a working J3 is more worth than any callback support for the FFI stuff... Also, in many cases you can work around callbacks (e.g., Windows, MacOS and X11 all support polling if you want to write your own window stuff).
I'm not saying that it'll never come - just not any time soon ;-)
- A.