When I was playing free demo levels on kongregate, I remember there was a command you could use to lock a room, so if you accidentally moved out the door, you'd just bounce off instead of losing all your progress and having to start over. I can't find anything like that in the downloaded version. Is it hidden or does it just not exist?

I just made a quick check in The Second Sky, but i think older games should use the same commands.

Use the SHIFT key. This should lock a room. Press again to unlock it.