anchor.diff:  
   class _RadialPainter extends CustomPainter {
     _RadialPainter({
  -    this.circles
  +    this.circles,
  +    this.bottomNavMaxWidth,
     });
   
     final List<_Circle> circles;
  +  final double bottomNavMaxWidth;
   
     // Computes the maximum radius attainable such that at least one of the
     // bounding rectangle's corners touches the egde of the circle. Drawing a
  
positive.code: 
    @override
    bool shouldRepaint(_RadialPainter oldPainter) {
      if (circles == oldPainter.circles)
        return false;
      if (circles.length != oldPainter.circles.length)
  
negative.code:                   bottom: 0.0,
                    child: new CustomPaint(
                      painter: new _RadialPainter(
                        circles: _circles.toList(),
                        bottomNavMaxWidth: _maxWidth,
                      ),
                    ),
                  ),
  