Right now if you zero on top of your workpeice the preview shows you the distance below the zero that the end mill goes. This is often my best check for ensuring that I won’t hit my work holding. I’ve started using a vice and I like to zero off a corner of the vice bottom/parallel so I don’t have to change my zero. Unfortunately while I can see from the side view that my paths stay above the zero a ways I have no way to quantify that.
I suspect that the code is just written to find the minimum Z value, and if its negative it displays it otherwise it doesn’t. It seems a simple fix that would help people who use vices quite a bit. This is also really helpful when zeroing off your table.
Another feature request that would take a bit more work would be to add some kind of scale in the pathing view of the preview but that’s not as reliable as the relatively simple fix above.