Powerbuilder - wow. Now THERE'S a blast from the past!
Does anybody actually still use Powerbuilder?
Anyway:
1. Mono/.Net is GUI, and supports data components:
http://www.mono-project.com/FAQ:_General
2. Lazaras and Free Pascal is also something you might wish to consider:
http://wiki.lazarus.freepascal.org/
There are many others - it depends on what you're looking for!