Скольжение это 3-4 пальцевый мультитач жест для Mac.
Источник:
http://www.firefoxfacts.com/2014/04/08/firegestures/
Here are the different mouse gestures you can use to execute various commands:
- Mouse Gestures (Move mouse with holding right-click)
- Wheel Gestures (Scroll wheel with holding right-click)
- Rocker Gestures (Left-click with holding right-click and vice versa)
- Keypress Gestures (Mouse gesture with holding Ctrl / Shift key)
- Tab Wheel Gestures (Scrolling wheel on the tab bar)
- Swipe Gestures (3 or 4 fingers multi-touch on Mac’s trackpad)