Thanks for the great software!
In Facing page view, I would like a scrollbar to appear when I move the cursor to the right edge of the window. Then I can drag the thumb up and down to quickly scroll through the document. This is better than a permament scrollbar because it doesn't waste space. I have seen some applications that show a thumbnail of the pages as you scroll instead of showing the real page. This works better when the pages can't be rendered fast enough.