[prog] Cross-platform GUI development

[jennyw]

I was wondering if any of you had suggestions for cross-platform GUI 
development.

I don't want anything fancy, just a platform that will let me develop 
mostly form based apps that run on Linux, Mac OS X, and Windows.

Java is an obvious choice, but I've heard that it's hard to get things 
to match up well on different platforms. wxPython looks very promising.  
Squeak will of course run bit-identical on every platform, and it'd be 
an easy choice, but Squeak apps look, well, like Squeak apps (i.e. 
non-native).  Other suggestions?

Thanks!

Jen