Hang on, hang on, don't get overexcited now.
Can MX load levels from one singe packed FPSC file? Or do you need to save each level as a seperate level?
I'm pretty sure the last thing is the case. Mr.Love claims he has created a save/load menu that allows you to load levels from a one single build game with many levels in it, not from seperate build level exes.
There's a huge difference between the two, a number of us have created menu launchers that do open sepereate exe file, but no one has yet build a menu launcher that can open levels from one build game.