When both sides of a 1.5 pt bar have a point level with a click 0.1 pt
from its end, the point of each side nearest the click is the end of a
segment, so the sides were not tried and an Alt-click there touched the
end edge.
A segment end now also counts when the segment is square there to the
line to the point, so splitting a side at the click gives the same
answer as an unsplit side.