YtgKNdBDTeZgYoDb<T> constructor

1. flutter_yfree package
2. documentation
3. extension/PopupWindow/popup_window
4. YtgKNdBDTeZgYoDb<T>
5. YtgKNdBDTeZgYoDb.new constructor

YtgKNdBDTeZgYoDb class