cancelDrag method
void
cancelDrag()
Aborts the current drag without mutating the tree.
Implementation
void cancelDrag() {
final session = _session;
if (session == null) {
return; // Per-session ticker: no session, so nothing can be ticking.
}
session.detachAll(SessionExit.cancel);
_pointerPosition.value = null;
_session = null;
notifyListeners();
}