Comment by skybrian

I think a good UI would be to prompt it with something like "how far is that hole from the edge?" and it would measure it for you, and then "give me a slider to adjust it," and it gives you a slider that moves it in the appropriate direction. If there were already a dimension for that, it wouldn't help much, but sometimes the distance is derived.

I'd love to have that kind of UI for adjusting dimensions in regular (non-CAD) images. Or maybe adjusting the CSS on web pages?