> There's a Qt toolkit that appears to
> have gotten to a usable alpha state in 2002 and then been abandoned.
> There may be others.
That is Ruby/Qt which is no longer maintained and only worked with Qt 1.x
and Qt 2.x. There is a newer Qt binding called QtRuby for Qt 3.x (and a
version for Qt 4.x is being developed). The Qt 3.x version runs on
Linux/Unix/BSD* and Mac OS X, and the Qt 4.x version will also run on
Windows.

QtRuby can be used with the Qt Designer UI building tool to visually layout
your UI, and produce a .ui file. You can either read in the xml .ui file at
runtime directly, or there is a QtRuby tool to convert it to ruby code.

There is some description here:
http://developer.kde.org/language-bindings/ruby/

You can download the source from here:
http://rubyforge.org/projects/korundum/

-- Richard