I believe we’re on the same page now. What I’m left wondering about is what feature of your widget enables some useful function beyond what’s here between default navigation (or Autodesk or Leica) orbit/zoom/pan of the scene or what happens during Define ground plane. I see your line, “missing one roll axis”. Is that the feature? If so, I have noticed sometimes I lose the level horizon, have to reset view to get it back.
I surely would love to see support for the SpaceMouse.