>Of the libraries you mention, wxWindows is the only other choice I'd
>recommend if you want strong cross-platform support and modern widgets and
>features, etc. I think wxWindows is great but it follows a pretty different
>design approach (under the hood) than FOX. I'm thinking specifically about
>the lightweight-versus-heavyweight approach to widget implementation. My
>understanding (which may be wildly incorrect) is that wxWindows ports are
>built on top of other platform-specific GUI toolkits; thus the distinction
>between wxGTK, wxMotif, etc.

You are correct that wx is built on top of GTK+. 
And I would agree that it is generally more of a 
heavyweight solution (as is its role model, 
MFC).

Kevin