ref: 241f68b543de62a800ff5cbf6c06580d45ab8a13
dir: /html/signpost.html/
Signpost <p> Connect all the squares together into a sequence, so that every square's arrow points towards the square that follows it (though the next square can be any distance away in that direction). <p> Left-drag from a square to the square that should follow it, or right-drag from a square to the square that should precede it. <p> Left-drag a square off the grid to break all links to it. Right-drag a square off the grid to break all links to it and everything else in its connected chain.