If you’re a former user of Mac OS 9, there’s a good chance you were a fan of tabbed windows. This feature let you drag a window to the bottom of your Mac’s display, where it became a pop-up “tab.” When Mac OS X came along, tabbed windows were left behind, much to the chagrin of many users. Sure, you can minimize windows to OS X’s Dock, but it’s not quite the same.
If you still miss tabbed windows all these years later, give Giovanni Donelli’s Sticky Windows 2.0 ( ; $15) a try. Once installed, you can drag any window to any edge of your screen—not just the bottom—and it will turn into a small tab. Click on the tab to toggle that window between full-size and tabbed view; the tab remains until you manually drag it from the edge of the screen. (If you’ve got multiple tabs around the edges of your screen, those with windows currently in full-size mode have their names greyed out.)

As with OS 9’s tabbed windows, you can drag items—such as files or clippings—over a tab; the tab’s window will switch to full-size view so you can drop the item in that folder or window. However, unlike OS 9, the window won’t automatically switch back to tab view when you’re done; you have to minimize it manually or, if the tab is set to “automatic” (see below), switch to another tabbed window.
Although I’m not a fan of this approach, Sticky Windows does offer a unique feature not found in OS 9: Automatic and Manual tab modes. In Automatic mode, a tabbed window is minimized automatically when another tabbed windows is viewed. In Manual mode, a tabbed window remains in full-size view until you manually minimize it; you can view several tabbed windows in full-size view simultaneously. You change the default setting for this feature in the Sticky Window pane of System Preferences; doing so changes the behavior of all new tabbed windows (windows already tabbed keep their original behavior). You can also change this behavior for individual windows by clicking-and-holding on the tab’s icon, or by option-clicking the tab itself. (The shape of the each tab indicates its current setting: tabs with rounded corners are set to Automatic; those with squared corners are set to Manual.)

Still, I wish there was a preference to emulate OS 9’s behavior so that the only time a tabbed window is in full-size view is when you’re actively using that window; in other words, when you switch to another application, or even a non-tabbed window in the same application, the tabbed window would automatically minimize.
Unfortunately, Sticky Windows doesn’t seem to get along with all applications. For example, when I tried to “tab” windows in Microsoft Word or Excel, I couldn’t work with those windows; when I switched them to full-size view, they automatically minimized to the tab after a few seconds. (Oddly enough, Microsoft Entourage windows worked as expected.) But Sticky Windows worked fine with most applications I tested. I also don’t like the fact that Sticky Windows lets you place tabs on top of one another—it’s easy to “lose” a smaller tab behind a larger one—and that you can’t disable tabs on particular edges of the screen (I found myself accidentally creating tabs when I was just trying to move a window flush with the top of my screen.) Finally, the developer notes that Sticky Windows is currently incompatible with accounts using OS X’s File Vault feature; this will apparently be fixed in a future version.
Oh, and one other minor complaint—and it’s admittedly very minor: When you tab and un-tab windows, Sticky Windows displays a “zoom” animation similar to Mac OS X’s minimize-to-the-Dock effect. However, instead of displaying a shrinking or enlarging view of the actual window, Sticky Windows shows a shrinking or enlarging colored box. And this box is pink. Now, I’ve got nothing against pink (or, as the developer calls it, magenta ); it’s a fine color. I just wish I could choose my own “zoom” color. (See, I told you this was a minor complaint.) Thankfully, the developer has indicated that this will be a preference in an upcoming version.
Sticky Windows 2.0 requires Mac OS X 10.4 or higher and is a Universal binary.