There are more and more gestures being added to the command repertoire in OS X and iOS, not to mention which are implemented and specifically what they do in each app
This is exactly what made Yosemite completely intolerable for me. It seemed that if I waggled my finger anywhere near the track pad the computer would perform some totally unpredictable action. Once I figured out how to shut them off except for the basic 1 (point), 2 (scroll), and 3 (page) finger gestures (as in Snowy), I was once again able to do useful work on my computer. Also had to reverse the default scroll direction.
