I played with this a bit, and found that it seems to give the wrong results. Check out:

https://imgur.com/a/0lGWShy

The numbers displayed (855, 144, 144) don't match the widths actually shown, the calculations look the same across all three panels even though they have different parameters, and the displayed calculations (e.g. -619 + 1000 = 855) don't add up.