SwingWT is a 100% pure Java library which very closely resembles the interface of Swing. The difference is that instead of using the Swing library, it drives native peer widgets from SWT.

Developers deploying to Linux can compile natively with GCJ and the applications can be distributed without a VM. Linux distribution makers could package many existing Java/Swing applications that previously could not be distributed in workable state.
Mature Swing UI designers can be used.