Is mouse wheel supposed to work on scroll viewer if ADT is created on a mesh?

I noticed in the example PG for the scroll viewer that the mouse wheel works to scroll the scroll viewer. In the example, the scroll viewer was added to a full screen ADT. When I tweak the ADT to create it for a mesh, the scroll viewer no longer works for it. Check out the PG here:

Is that expected? Any way to get the mouse wheel to work with the scroll viewer even if the ADT is not in full screen mode?

Will be fixed by: