Very good point. I don't use Alt F1-5 on purpose, but I DO use shift F4 to change between window/full. And, out of muscle memory habit, I do occasionally hit Alt-F4, which currently is safe.
But if Alt-F4 closes LFS then it'll potentially cause problems. Maybe Alt-F4 needs some 'confirm' dialog, but one that doesn't get in the way of driving if you just happen to be changing between window and fullscreen on the backstraight or something.