OS X Mountain Lion: The Missing Manual

Desktop & Screen Saver

This panel offers two ways to show off Mac OS X’s glamorous graphics features: desktop pictures and screen savers.

Desktop Pictures

Mountain Lion comes with an expanded collection of desktop pictures, ranging from National Geographic–style nature photos to plain solid colors. To install a new background picture, first choose one of the image categories in the list at the left side of the window, as shown in Figure 9-9.

Your choices include Desktop Pictures (muted, soft-focus swishes and swirls and a few nature shots); Nature (bugs, water, outer space); Plants (flowers, soft-focus leaves); Art (a collection of famous paintings by Monet, Dégas, Seurat, and other canvas superheroes); Black & White (breathtaking monochrome shots); Abstract (swishes and swirls with wild colors); Patterns (a pair of fabric closeups); and Solid Colors (simple grays, blues, and greens). Some of them are new in Mountain Lion, and really nice.

FREQUENTLY ASKED QUESTION: How the Mac Knows Where You Are

OK, I’ll bite. To set my time zone automatically, the Mac has to know where I am. It doesn’t have GPS. So how does it do that?

Metropolitan areas today are blanketed by overlapping WiFi signals. At a typical Manhattan intersection, you might be in range of 20 base stations. Each one broadcasts its own name and unique network address (its MAC address—nothing to do with Mac computers) once every second. Although you’d need to be within 150 feet or so to connect, a laptop or phone can detect this ...