Object Workbench plugin

Hi all,

I teach introductory programming using BlueJ. I think it works nice
for beginners, but not for 'real' development. However there is one
feature that I do really like, and that is the object workbench. The
ability to instantiate an object and call its methods for testing
purposes is just so nice.

I've searched the plug-in archives, and this list, but I haven't seen
anything that sounds like what I want. Anybody know if something
like this is around? Is it possible to write a plugin to do what I
want?

Thanks

Brad