anchor.diff:          new AnimatedCrossFade(
             firstChild: new Container(height: 0.0),
             secondChild: new Container(
  -            margin: const EdgeInsets.only(
  -              left: 60.0,
  -              right: 24.0,
  +            margin: const EdgeInsetsDirectional.only(
  +              start: 60.0,
  +              end: 24.0,
                 bottom: 24.0,
               ),
               child: new Column(
  
positive.code:             ]
            ),
            new Container(
              margin: const EdgeInsets.only(
                left: 12.0
              ),
              child: _buildHeaderText(index)
            )
          ]
  
negative.code:   Widget _buildVerticalBody(int index) {
      return new Stack(
        children: <Widget>[
          new PositionedDirectional(
            start: 24.0,
            top: 0.0,
            bottom: 0.0,
            child: new SizedBox(
  