The PushMeAround Puzzle revamped.
File in LittleThings61.st, find the LittleThings category and the ArrangedTiles
class in your browser and read the class comment. Or (if you are too impatient
to do it) make sure you have a Transcript window opened (important!),
write "x := ArrangedTiles new. x runAway" to a Workspace, select it, "do" it,
and watch. (When you have had enough of watching, you have to break the process
manually as instructed by the application's display panel.)