I had bug in my code, where I was calling mapToScene (incrementalMouseMotion), to implement smooth scrolling. As long as the view and scene coordinate systems are aligned, this returns a proper distance. But once I called view.translate() with that distance, of course I got the typical complaint, my graphic items just danced a little since then the coordinate systems were not aligned on subsequent mouse motions.

Am I missing something in the API? I know its easy to work around, but it constrains my approach.