Well, I found out a little. More importantly, I found where to find more on this description language. Unfortunately, it doesn't solve my problem.

The problem seems to be that SC is "scaling down" the offset of the mouse from the origin. When the 2D Geometry tab is active, there is a small indicator in the lower right that shows where SC thinks the mouse pointer is in the X and Y.

So to get a reference to my part, I go to 2D Geometry and define a couple of points in the Sprutcam source "Debugger" window.

P11=X(-8),Y(0),Lr1
P12=X(-8),Y(-4),Lr1

(These lines define points at (-8,0) and (-8,-4) and puts them on layer 1. That makes them visible. If I put them on layer 0 (Lr0), I won't see them unless I click right on them.)

If I hover over P11, the indicator at the lower right correctly indicates that I'm at (-8,0), and if I hover over P12, it correctly indicates that I'm at (-8,-4). However, if I hover slightly below P11, at say Y(-0.2), now it says I'm at X(-4.22). In other words, if the pointer "snaps" to a manually created point, Sprutcam correctly figures the offset from the origin. If I move off in only one axis, it appears that it's scaling the offsets to slightly more than 1/2. This occurs in X and Y.

What's going on, here? Is there some obscure setting somewhere that causes SC to do this? I'd really like to get back to making parts.

-Mark