With lower resolution monitors (1280 x 1024 for example), some puzzles can prevent the player from exiting them. Basically the puzzle image doesn't scale down properly, and in order to exit that screen one has to click on the area which is off screen, which simply locks the player on it.

I saw it happening on a small monitor on the baby puzzle (the mobile) and on the green control screen in the big room. I tested it with bigger resolution monitor (1920 x 1200) - and it worked OK. Both system are using current Debian testing Linux, x86_64.

You can also set Esc key as an exit key for such puzzles, which would make things easier in general and could be a workaround for such bugs.