I would have thought it would be a touch event, but it's actually a normal scroll event. The only difference I can see is that it has the ctrl bit flipped.
I understand that, but do any of the touch events fire in parallel? Like, just before the pinch happens, is there not a touch start even for when the fingers touch the screen? The idea is to change the rate of the normal scroll event only if there are fingers on the screen.
Here's the stackoverflow answer: http://stackoverflow.com/questions/15416851/catching-mac-tra...