anchor.diff:            ..lineWidth = 1
   
             ..beginPath()
  -          ..strokeStyle = OutlinableAction.LIGHTER_LINE_COLOR
  +          ..strokeStyle = LIGHTER_LINE_COLOR
             ..rect(offset.x, offset.y, size, size)
             ..stroke();
   
  
positive.code:         ctx
              // draw a white cross
              ..beginPath()
              ..strokeStyle = OutlinableAction.DARKER_LINE_COLOR
              ..moveTo(offset.x, offset.y)
              ..lineTo(offset.x + size, offset.y + size)
              ..moveTo(offset.x + size, offset.y)
  
negative.code: 
        ctx
            ..beginPath()
            ..strokeStyle = DARKER_LINE_COLOR
            ..rect(offset.x + 1, offset.y + 1, size - 2, size - 2)
            ..stroke();
      });
  