STR: 1. open the preferences (tested on OS X on my mbp, not 100% sure it'll reproduce with a mousewheel). 2. 2-finger-scroll/swipe from the center of the page to start the page scrolling. ER: scroll and stop smoothly close to the bottom (depending on how vigorously you scroll/swipe) AR: stop scrolling abruptly as soon as your mouse pointer is over the search engine list; further attempts to 2-finger-scroll while the mouse is over the list don't work. Jared, is there a tracker for this work?

This bug existed in the old preferences but since it was very hard to get a scrollbar there most people never encountered it. We're tracking this work under bug 1324168.