detach method
Unregister the given position with this controller.
After this function returns, the animateTo and jumpTo methods on this controller will not manipulate the given position.
Implementation
@override
void detach(ScrollPosition position) {
assert(_positionToListener.containsKey(position));
_positionToListener[position]!.forceCancel();
_positionToListener.remove(position);
super.detach(position);
}