anchor.diff:  
               // draw a black cross
               ..beginPath()
  -            ..strokeStyle = 'rgba(0,0,0,0.5)'
  +            ..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)
  
positive.code: 
  class FloatLayerAction extends OutlinableAction {
    static const FLOAT_PIXEL_SIZE_FACTOR = 0.85;
  
    final PixelCanvasElement canvas;
    final FloatLayer floatLayer;
  
negative.code:         ctx
              // draw a white cross
              ..beginPath()
              ..strokeStyle = CELL_OUTLINE_COLORS[1]
              ..moveTo(offset.x, offset.y)
              ..lineTo(offset.x + size, offset.y + size)
              ..moveTo(offset.x + size, offset.y)
  