I'm going to side with mcomb and dbrashear here. Grafting the Empire code into emphatic made sense, because it's very small code that's related to the player app itself (queueing songs.) GPSapp, on the other hand, has nothing to do with a "better player experience" which is what emphatic's designed to do.

HOWEVER, it would be pretty trivial for me to create a pipe that GPSapp (or any other app) could write to from the background, and I could display any data that comes in on that pipe as a custom display mode element. I'd have to do some thinking on how to best handle that, and maybe a special (but simple) format for data that's written to the pipe, but beyond that, it doesn't seem that hard.

Now, the real question is if we had that, would GPSapp and emphatic play nicely together? For that to work, GPSApp would have to have a background thread that would be reading the GPS stuff and writing it to the pipe. If GPSapp ever needed to be brought to the foreground, there might be problems, as multiple apps accessing display/input is not handled very well.

But if we can agree on an interface, I'll give it a shot.