public void DropItem (Item item) {
if (!item.canDropdown) return;
if (item.transform.parent == transform) {
item.transform.localPosition = Vector3.forward;
item.transform.parent = null;
item.gameObject.SetActive (true);
items.Remove (item);
// --- events
item.OnItemDropDown (behavior.gameObject);
EventItemDrop (item.gameObject);
}
}