anchor.diff:      final size = pixelSize * FLOAT_PIXEL_SIZE_FACTOR;
       final margin = (pixelSize - size) / 2;
       final marginVector = new Point(margin, margin);
  -    floatLayer.forEach((point, color) {
  +    floatLayer.forEach((Point<num> point, color) {
         final offset = (point * pixelSize) + marginVector;
         ctx
             ..setLineDash([])
             ..lineWidth = 1
   
             ..beginPath()
  -          ..strokeStyle = 'rgba(0,0,0,0.5)'
  +          ..strokeStyle = CELL_OUTLINE_COLORS[0]
             ..rect(offset.x, offset.y, size, size)
             ..stroke();
   
  
positive.code: 
  class FloatLayerAction extends OutlinableAction {
    static const FLOAT_PIXEL_SIZE_FACTOR = 0.85;
  
    final PixelCanvasElement canvas;
    final FloatLayer floatLayer;
  
negative.code: 
              // draw a black cross
              ..beginPath()
              ..strokeStyle = CELL_OUTLINE_COLORS[0]
              ..moveTo(offset.x, offset.y + 1)
              ..lineTo(offset.x + size - 1, offset.y + size)
              ..moveTo(offset.x + size, offset.y + 1)
  