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() {
_transition.removeListener(markNeedsPaint);
_pressed.removeListener(_handlePress);
_sparkles?.removeListener(markNeedsPaint);
_validForMouseTracker = false;
super.detach();
}