Ron
We seem to have differing expectations. I assumed that inside, groove, and outside were essentially the same and merely offered the convenience of the user not having to allow for tool radius when sizing the path. This is what seems to be the case with the polygon tool, and I am at a loss as to see why the rectangle uses a different approach. Anyway, I now have a much better understanding of your way of doing it.
By the way, I tried selecting groove, leaving everything else unchanged, and got a rather strange looking toolpath.
Allan