[TriLUG] Cross Platform GUI

[P. L. Charles Fischer]

I am looking for a cross platform GUI library.  I need Microsoft Windows, 
Linux and Tru64 UNIX support.  If the Mac is supported that would be a 
plus.  Some of the programs developed will be released using the GPL others 
will be proprietary.  The meat of the programs will be written in C, so a C 
or C++ library makes life a lot better.

I am looking at wxWindows, but would like to know if there are better options.

Thanks
Charles Fischer