I see no arrows at top and bottom of the right-hand scroll bar for doing this, only the scroll bar itself. With very long webpages or documents, using the scroll bar gives no fine control over scrolling up and down a single page or a few pages at one time.
With Document Viewer, I am trying to scroll up and down a single page of the PDF I am reading, because the whole page is not shown on the screen at one time. Even if I try to use the scroll bar to move up and down the page, the scroll bar doesn't move with the mouse pointer and the page inexplicably starts drifting up or down of it's own accord, out of my control.
English, please!