After using REBOL, I found the "standard" GUI functionality in Python for creating interfaces so unhappy I used pyPEG to write a DSL parser that would turn REBOL-style interface descriptions into introspective wxPython GUI's.

I say REBOL-style, since it was superficially similar to REBOL (or REBOL/VID, if you prefer), the full power of the Visual Interface Dialect requires an actual REBOL interpreter...! Instead, I used mostly static layouts and a simple escapement to call Python handlers as necessary.