Hi Tony yeah you can only grab on to a part of the wheel for that mode currently, which places the starting reference point at a kind of semi-arbitrary location.

Object snaps are intentionally turned off in that case so that you don't think you're getting an accurate result by snapping the ending point on to something, since the start point was rather arbitrary.

I have an idea of improving this though, I think in the ortho views I can allow clicking on a snapped point and then dragging from there to do the rotate. I've been planning on giving that a try. If it works out it should be a nice way to do a quick "accurate from a reference point" type rotation.

I can't really do that for the 3D view though since the rotation is also controlled by which particular wheel out of the 3 that you clicked on for the drag.

- Michael