GroovySWT is a wrapper around SWT, the eclipse Standard Widget Toolkit. It allows you to easily write Eclipse SWT applications by using Groovy's builder mechanism.
Here is some SWT code using native Groovy:
Here is the same example using SwtBuilder:
Here is another example explicitly creating a script class and assuming guiBuilder is passed in via a binding:
The sources (and README.txt telling you how to set up the libraries and dll's) can be found here:
The jar file compiled against Eclipse SDK 3.2.1 jars can be found attached: