Scroll Reverser for Mac, at http://pilotmoon.com/scrollreverser
In preparing for Lion, I’ve decided to see how the reverse scrolling (i.e your fingers move the page and not the scrollbar) would pan out on my MacBook. For web pages, I took to it immediately and it felt right straight away. As I went a little further, with documents and editing in TextMate, it also felt natural with only a couple of slip ups reverting to previous behaviour, especially when I was editing rather than just viewing. Indeed, when I really needed to get down to some serious editing, reverse scrolling had to be switched off it was such a distraction!
My issues became a lot worse when it came to Finder though. It didn’t “feel right” when I was scrolling the display of folders and documents, and I repeatedly kept following my instincts and found myself trying to scroll with the scrollbar. I wonder if this is because I don’t feel like I’m moving a document or piece of paper, or maybe, I’ve become used to reverse scrolling through the use of my iPhone – which especially make sense when I’m scrolling web pages, but the iPhone lacks any kind of file browser and I’ve never had to scroll through a similar interface. This also might explain my difficulties when editing documents – something I rarely ever do on an iPhone, as I’m just a consumer of media on that device rather than my MacBook Pro where I’m both consuming and creating.
In summary, the reverse scrolling, which will be default in OS X 10.7 Lion, is natural for web pages and for viewing documents but frustrating for Finder windows where, even if I’m using reverse scrolling fine everywhere else, it just doesn’t “feel right”.