Suggested GUI framework for Mac and unix?

[Russell E. Owen]

I have a free cross-platform Python GUI application that has to run on 
Mac and linux. It is presently written in Tkinter, but for various 
reasons* it may be time to switch.

I've heard many good things about wxpython and qt, but not used either, 
and am wondering if somebody could tell me if either (or both) would 
meet the following needs:
-  Reliable on mac and linux. (I see that wxpython now runs under Cocoa 
but I've not seen any reports on how well that went.)
- Compatible with matplotlib.
- Able to display (grayscale) images with arbitrary zoom. I currently 
use PIL with Tkinter's Canvas widget for this.
- Compatible with a sound library for playing sound cues. I presently 
use pygame for this and have been considering switching to PySDL.
- Compatible with Twisted Framework.
- Prediction is hard, but indications of a long-term future would be a 
definite bonus.

-- Russell

*I have no wish to disparage Tkinter. I personally like it and am very 
grateful to the developers. However, several issues are driving me to 
look for alternatives:
* There is a known crashing bug in recent versions of Tcl/Tk that keeps 
me at 8.5.11. Unfortunately I've not found a workaround.
* Tcl/Tk 8.5.11 is not compatible with Mavericks unless one runs in 
32-bit mode.
* There are known issues with the Tcl/Tk event loop since the switch to 
Cocoa. These are unlikely to be fixed, though in many cases it is 
practical to work around them. This is more of a long-term worry than a 
concrete problem.