Autoleveller

I'd like to see the app remember the folder I last opened (rather than default to the Documents folder - that's a good first default for sure, but I keep all my PCB stuff in a completely different hierarchy), and I'd especially like it to retain the fact that I use Mach3 not LinuxCNC.

Persisting settings like this has been requested a few times in the past. This would be fairly simple addition too, but I'm currently restructuring things and possibly adding exiting new CNC software tools so when this will be done I cannot say.