One new feature of OS X Lion that is sure to win both fans and foes is the ability for apps to go full-screen. Apple teased us with this last year when updates to several of the iLife apps -- iPhoto, iMovie, and GarageBand -- brought the ability to take over the entire screen of a Mac with a single click. Now in Lion, more of the standard Mac apps are full-screen apps. After using Lion and these apps for a while, my feeling is that full-screen apps are a good idea, but in the initial OS X Lion implementation they're inconsistent.
How do full-screen apps work? You can tell when you're in one thanks to the double-ended arrow up in the upper right-hand corner of the app window. With a click, the app takes over the entire window on your Mac. That's right -- the menu bar and dock are nowhere to be seen. The app also gains its own Space and is accessible through Mission Control. If you need to get to the menu bar, moving your cursor to the top of the screen reveals it again. Want to get back to a normal window? Just press the Esc key on your keyboard and you're there.
What apps are full-screen enabled at this time? As mentioned earlier, iPhoto, iMovie, and GarageBand got the full-screen treatment last year. Safari, Mail, iCal, Preview, DVD Player, QuickTime Player, and Photo Booth have also been updated to take advantage of full-screen.
Using these apps at the same time in full-screen mode is wonderful. You're focused on the task at hand, but when you need to jump over to another full-screen app, one quick gesture brings you to Mission Control where you can swipe over to the other app; a left-right swipe can switch you as well. It's quick and seamless, and especially on a small-screen Mac like an 11.6" MacBook Air, it's a wonderful way to work.
I love what Apple did with Photo Booth, which of course is probably the most popular app for people who are trying out Macs in Apple Stores. When Photo Booth goes full-screen, the photo window is framed by beautiful wood and a red velvet curtain. It's much more exciting than the boring windows we've seen for years.
So what's with iWork? At least at the time this post was written, Keynote, Pages, and Numbers were full-screen, but didn't use the double-ended arrow to jump into that mode. That seems very inconsistent, but it wouldn't surprise me if an update was on the way to add the Lion-specific full-screen capability to iWork.
Other Apple apps that aren't full-screen happy include FaceTime, iChat, Address Book, iTunes, the Mac App Store, Chess, Dictionary, iDVD, Image Capture, iWeb, Stickies, TextEdit, and pretty much all of the Utilities. I was only able to find a handful of third-party apps that went full-screen (Pixelmator is a perfect example), but they didn't properly create their own Spaces. That indicates to me that developers have a way to go to provide consistent support of full-screen mode.
From my point of view, full-screen apps make a lot of sense, as they make the best use of available display real estate. While some apps can seem somewhat absurd on a large 27" display, it's nice to be able to concentrate on one application and not have anything else get in the way. When you want to slip over to another full-screen app, one or two quick gestures gets you there easily. As more and more apps become available in full-screen mode with support for Spaces, I think we'll see full-screen apps hitting their stride.