revert method
Reverts this operation from the current list.
Modifies current in place and returns the operation itself (or reversed op).
Implementation
@override
OverlayOp revert(List<InteractiveOverlayImage> list) {
final old = list.findByKeyOrNull(key);
if (old == null) return this;
final prev = _withCorner(old, corner, from);
list.updateByKey(key, prev);
return this;
}