StepTalk is the script environment of GNUstep. It is powerful to access GNUstep objects and applications from various ways. For programmers who want to add script support in their applications, they can look at the "Application Scripting". By simply adding some supporting code and interface, users can use script to access the functions the appliction offers.
StepTalk comes with good documentation and examples. Now, GNUMail uses StepTalk for scripting.