How to Make the Most of Dock Icons in Apple OS X Lion

Some of the good ideas in OS X Lion look a lot like Microsoft's best ideas for Windows 7. Click and hold an application's Dock icon and you'll see either a list of that application's recently-opened and currently-open documents, or—as shown here for Mail—a list of currently-opened windows and a few frequently-used functions, such as creating a new message or note. This is a lot like Windows 7's smart taskbar icons, but Lion adds a few ingenious twists.

For example, if a document-handling application like Pages is open, and you hold down its Dock icon, you'll see a list that starts with recently-used files, then a list of currently-opened files. Below that is a menu item that says "Show All Windows;" click on it, and the desktop disappears, replaced by a large-size image of the currently opened documents occupying most of the screen, and with a row of thumbnail-sized previews of recently-opened documents below it. You can click on any of these previews to switch to the document if it's open or open it if it's closed.

If the same application is closed, and you hold down its Dock icon, then the "Show All Windows" menu item is replaced by "Show Recents." Click on this item, and a row of thumbnails appears, and you can click on a thumbnail to open the application and the document.

This system has one potential gotcha, which is that Lion doesn't check whether a recently-used file actually exists on your disk, so you can click on one of those preview thumbnails, and nothing will happen. This behavior is exactly the same as the behavior of the recently-used-files lists in other applications (including Windows) applications, but I was surprised to see it in an OS as otherwise helpful as Lion. A quick hint: the giveaway that a document no longer exists is that its preview icon is completely blank.
