Finally found something to post about again: Koopa! I spent the last week updating the GUI applications. Rather than having two separate ones (one for batch processing, one for visualising a single file) I have now integrated them both.
(JTabbedPanes look a bit ugly on the Mac, but I don't want to spend time changing that. It works, and that's enough for now.)
In addition you can now simply drag-and-drop files onto the Koopa GUI and it will try to parse them. And once parsed you can easily navigate from a selected part of some source code to the grammar rule which parsed it.
All this will hopefully make for more a more useful and usable application.