Among the many changes in Lion (Mac OS X 10.7), one of the most controversial is a new way of scrolling. In Lion, when you drag two fingers downward on a MacBook’s trackpad or Apple’s Magic Trackpad ( ), or spin your mouse’s scroll wheel towards you, the content of the current document or window scrolls down, as well. In other words, scrolling is backwards compared to how we’ve been doing it for the past decade and a half.

The initial furor over this change is starting to die down as people have either gotten used to the New Way or used Lion’s option, in System Preferences, to switch back to the Old Way. But even among those who’ve adjusted to—or, heck, enthusiastically welcomed—this inverted scrolling, there are a couple persistent complaints. The first is that there’s no way to configure Lion to use the new scrolling orientation with trackpads while maintaining traditional scrolling with mice and trackballs. (Count me in this group—I’ve mostly adjusted to the new way of scrolling on my trackpads, likely because it’s similar to the way I touch-scroll on my iPhone and iPad, but I can't quite acclimate to it when using my mouse’s scroll wheel or my trackball’s scroll ring.) The second is that some people who like this new direction for vertical scrolling haven’t yet taken to inverted horizontal scrolling.

Before Lion was released, I wrote about a nifty utility called Scroll Reverser that lets you invert scrolling. At the time, it was designed to let Snow Leopard (OS X 10.6) users get a head start on Lion’s new scrolling; it remains a useful way for Snow Leopard users to invert scrolling.

But since that article, Scroll Reverser has received a number of significant updates, and the current version works great in Lion to let you customize scrolling beyond OS X’s simple inverted/traditional checkbox. Specifically, Scroll Reverser addresses the aforementioned shortcomings of Lion’s scrolling options.

Launch Scroll Reverser, and its systemwide menu lets you quickly adjust your scrolling preferences. By default, all scrolling is reversed (from whatever your System Preferences setting is) for all input devices. You can quickly disable Scroll Reverser by choosing Reverse Scrolling from the menu to uncheck it. (Scroll Reverser affects only traditional scrolling; it doesn’t affect other Multi-Touch gestures.)

But the Preferences sub-menu is where Scroll Reverser’s real utility lies. Here you can choose which devices—trackpads, mice, and tablets—are affected by Scroll Reverser. (The Mouse category includes most trackballs.) In other words, if you want to keep Lion’s inverted scrolling for your trackpads and tablets, but use traditional scrolling when using a mouse or trackball, you can do so. You can also choose whether to reverse both horizontal and vertical scrolling, or just one or the other.

There are a couple limitations here. One is that Scroll Reverser depends on information from Mac OS X to determine the type of each device. For example, the non-Multi-Touch trackpads on older Mac laptops are treated as mice, rather than trackpads, as are the trackpads on some third-party keyboards with built-in trackpads or touchpads.

Another is that your horizontal and vertical settings apply to every class of device (trackpad, mouse, or tablet) you’ve chosen to “reverse.” I’d like to see separate horizontal and vertical settings for each type of input device. In addition to being more flexible, such a settings interface would actually make configuring Scroll Reverser less confusing—between Lion’s own scroll-direction setting, Scroll Reverser’s main on/off setting, and the various settings for directions and device types, sometimes figuring out the right combination of settings to get your desired results feels like an LSAT question.

Still, Scroll Reverser is a welcome solution for customizing Lion. For some people, it just may be the thing that finally gets them using Lion's new scrolling—at least on some of their input devices.

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