This probably is not important but I didn't see it mentioned anywhere in the documentation, so I might as well point it out.
While the usage of the game_restart function is usually only for debugging (so normally this won't be an issue), I noticed that the buttons duplicate, so you end up having a stack of buttons after restarting the game a few times. I assume it has to do with the gameframe_init function being repeated on each game start without a proper cleanup when the game restarts.
How the buttons look after restarting the game twice: