GPS settings don't stick

There are at least a couple of problems with the GPS settings in Vehicle Commander:
- [ ] When I choose Simulated GPS and browse to a .gpx file, it doesn't always work. Sometimes it uses the new .gpx, sometimes it still uses the old .gpx, and worst of all, sometimes it seems to use both, jumping back and forth between the two.
- [ ] When I choose Simulated GPS and browse to a .gpx file and then exit the application, when I launch the app again, it reverts to the built-in .gpx. Instead, it should remember the last .gpx file in use. If that .gpx no longer exists, then it could use the built-in .gpx.
- [ ] Following the previous item: if I then try to choose the same .gpx that I chose before, it doesn't seem to work. The built-in .gpx is still used.