ConstThe diagonals are not here: they would run corner to corner through both inner rules, and nearest-edge picking cannot separate three lines that all cross the same point.
The order is the tie-break for a pointer sitting exactly where two lines cross, so the OUTER edges come first — a click on the left edge at its midpoint is aimed at the block's outline, not at the inner rule that happens to end there. The crossing of the two inner rules is not a tie at all: it is its own target (see edgesAt).
The edges the diagram lets you click — the six that a block of cells can draw.