3 Connect all the squares together into a sequence, so that every
4 square's arrow points towards the square that follows it (though the
5 next square can be any distance away in that direction).
8 Left-drag from a square to the square that should follow it, or
9 right-drag from a square to the square that should precede it.
12 Left-drag a square off the grid to break all links to it. Right-drag
13 a square off the grid to break all links to it and everything else
14 in its connected chain.