Four bar handles at the midpoints of the sides, each moving only its
own side along the axis across it. The overlay reports an edge as 0.5
on the axis it does not move, so the anchor Rust takes is the middle
of the far side.
Under a ratio lock the dragged axis leads. with_aspect grew the short
axis onto the ratio, which for an edge pulled inward made the untouched
axis the leader and pushed the edge straight back out.