While this is rather late, recently looking at this it suddenly clicked.
If you notice in the error it states a class NSHIObject (HI I am guessing stands for Human Interface) this has to do with the backend that wxPython uses, the archaic Carbon (as in this case) or the updated Cocoa. In earlier versions only Carbon was available but with 2.9.5 (IIRC) Cocoa is available (and I believe it has sense moved to 3.0 with Cocoa or Carbon ). Simply reinstall with a cocoa version and it works.