Firefox 34 just went to the F20 stable updates. The bookmark sidebar
scrolling behavior has changed and I can't find any reference to it, though
I probably just don't know what to search for. You used to be able to
middle-click on the scrollbar to move it to an arbitrary position, or
left-click on it to move it up/down one page at a time. Now left-click moves
the scrollbar to an arbitrary position (same as the old middle-click), and
middle-click does nothing. Is there some way in FF34 to scroll up and down
the bookmark sidebar one page at a time?