J.B.,
Steve can probably answer this better, but I'll give it a shot. I've used
JUnit and JFCUnit, but I haven't explored SWT testability.
Eclipse provides a plug-in called org.eclipse.swt.tests that you can download from their CVS site. This contains many, many JUnit tests for SWT widgets and you can customize them for your use. There's a similar package for org.eclipse.jface.tests.
Also, the Eclipse Test & Performance Tools project is shaping up to test everything Eclipse-related and more. I don't know if it's ready for prime time, but it's worth investigating.
I'll keep looking though, and I'll keep you posted if I find anything.
Matt Scarpino