Option key unlocks all sorts of wonders

In past columns, we've run the gamut from reviewing Mac computers and software to keeping you informed about data security and sharing videos on the Web. Today, however, I have a more lofty goal: one key on your keyboard.

This isn't just any key. It unlocks all sorts of hidden features and troubleshooting modes, is supersimple to use, and is already included on whatever Mac you use.

I present to you the Option key!

OK, perhaps you're not initially impressed, but give me a chance.

Mac software, in general, is pretty transparent. Features are found either in a program's interface — think of the buttons in iTunes' single window — or from menus. Sometimes a feature or option is tucked into a preference window or in a palette. But mostly you can find what you need by poking around within a program.

The Option key, however, unlocks things that aren't immediately apparent.

Let's start with some basics.

Assume you have two applications open and visible on your screen, and you want to hide the active (front-most) program. You could go to the application's menu and choose Hide [name of application], but it's much easier to just press the Option key (at the lower-left corner of the keyboard, just to the right of the Control key) and click the other application. The first program is still running, of course, but it's hidden.

Similarly, let's say you have a Web browser such as Safari or Firefox running, with four or five windows open. To clean up your view you can minimize each window so that it appears as a thumbnail in the Dock, but doing each one is time-consuming. Instead, Option-click the yellow Minimize button at the upper-left corner of one window to automatically minimize all open windows.

The Option key really lives up to its name when you hold it down while launching some applications. It often brings up options that are unavailable elsewhere in the programs.

For example, if Microsoft Entourage appears to be misplacing e-mail messages or assigning events to odd dates, hold down the Option key when you launch the program. Instead of Entourage's typical Mail or Calendar view, you'll see a special dialog that gives you the option to rebuild Entourage's central database file where all of your information is.

What reminded me of the wonders of the Option key this week was a little-known feature of iPhoto.

I've reached the point where I don't have enough free disk space on my MacBook Pro's hard drive to hold all of my digital photos. The easy solution is to store them on an external hard drive, but iPhoto doesn't differentiate between locations — it wants everything in one place.

However, holding Option when launching iPhoto brings up an otherwise inaccessible dialog that lets you choose a different iPhoto library.

If you use a desktop Mac in one location, this hidden feature may not be interesting. But if you use a laptop in several locations, as I do, this capability lets you maintain separate libraries in each place. The feature could also be used to keep your images separate — for example, if you want to access both personal and business images without intermingling them.

To create a new library, hold Option at launch and click the Create Library button. Then, specify the location (such as an external hard drive).

When you want to switch to another library, simply hold Option at launch, click Choose Library, and navigate to that iPhoto library folder.

Of course, Option isn't the only magic modifier key on the keyboard. In iPhoto, hold Option and Command (the Apple key) at launch to bring up a dialog with options to rebuild iPhoto's image thumbnails or the iPhoto Library database.

iTunes also offers the capability to create and choose music libraries, but the process isn't as smooth: iTunes loses track of song file paths, requiring you to also specify the location in the iTunes preferences and re-link the files the next time you want to listen to them.

Feel free to explore your options with this magic key. Applications' Help documentation will often reveal previously unknown Option key combinations and features, or you can Option-click with abandon (making sure you have a good backup of your data, of course). You may find a combination that saves you time and trouble later.

Jeff Carlson and Glenn Fleishman write the Practical Mac column for Personal Technology and about technology in general for The Seattle Times and other publications. Send questions to carlsoncolumn@mac.com. More Practical Mac columns at www.seattletimes.com/columnists.