I was trying to embed MultiPaX into a GATE pipeline using the gapp file mechanism.
I noticed that when doing so, MultiPaX dies with a null pointer exception because in lines 145 and 196 it assumes a non-null StatusListener object. Commenting these lines out appears to work. I'm not sure if that's the best approach to the problem, but I thought you may want to be aware of the potential problem.

Gui Status Listener
Thanks for the comment. We were indeed not checking whether the GUI is used or not. In the next release we will fix this...