Gah, I've slapped in my path finding library. So now, with a few tweaks, mouse movement and path finding, is hacked in.
There's a problem though. I split the world into multiple maps and path finding across these maps, probably means changing my path finding code. The multiple maps buisness has always been a headache.
For now I'm happy to get path finding working on a single map. And worry about moving over map boundaries later.