detach method
Mark this render object as detached from its PipelineOwner.
Typically called only from the parent's detach, and by the owner to mark the root of a tree as detached.
Subclasses with children should override this method to
detach all their children after calling the inherited method,
as in super.detach().
Implementation
@override
void detach() {
// Unregister this shape when removed from tree
_findLayer()?.registeredShapes.remove(this);
super.detach();
}