Use case

Positioned widget can be positioned using start and end with directional factory.

https://api.flutter.dev/flutter/widgets/Positioned/Positioned.directional.html

RelativeRectTween of PositionedTransition widget can only be set by left and right.
If we need to consider both TextDirection.ltr and TextDirection.rtl, code will be verbose.

https://api.flutter.dev/flutter/rendering/RelativeRect-class.html

Proposal

RelativeRect.fromDirectional would be great!

RelativeRect.fromDirectional(
    textDirection: TextDirection.rtl,
    start: 10.0,
    top: 20.0,
    end: 30.0,
    bottom: 40.0,
);