When I am editing (haven’t gotten beyond that to test in other contexts), I can click and drag the highlighted part of the scrollbar just fine. What I cannot do is get the page to scroll at all when I click on the scrollbar above or below the highlighted, active part. What I expect is that it will scroll up or down a page when I do that. This is an accessibility issue, as not everyone does click+drag easily and using the scrollwheel (which may be problematic for some people also) is less accurate for paging up or paging down. The page up and page down keys don’t do anything either. Neither do the arrow keys. I would expect that if I did not have any objects selected, the arrow keys would scroll the whole page. Nothing happens.
Also not good is that if I have objects selected and I want to scroll, clicking on the scrollbar above or below the active part deselects the objects. I would expect that they would stay selected.