private void GUIItem(ref ItemEnum item)
        {
            item.name = EditorGUILayout.TextField(item.name);

            EditorGUILayout.Space(50.0f);

            item.number = EditorGUILayout.IntField(item.number);
        }
        private void AddItem(Rect rect)
        {
            int      count   = _list.count;
            ItemEnum newItem = new ItemEnum();

            newItem.number = count == 0 ? 0 : _list[count - 1].number + 1;
            newItem.name   = "Item" + newItem.number;
            _list.AddItem(newItem);
        }