Unlock thumbnail previews for Firefox 3.6 on Windows 7

Firefox users, if you're running the most recent release on Windows 7 you need to make a tiny tweak to your browser's configuration. It defeats the purpose of Aero's cool taskbar thumbnails feature if you have to open a window before you can scan which browser tabs you have open. IE8 shows all open tabs in thumbnail previews when you point to its icon. So how do you add the same feature to Firefox 3.6? I explain.

Firefox users, if you're running the most recent release on Windows 7 you need to make a tiny tweak to your browser's configuration. Some early adopters wrote about this topic back in November, in conjunction with the 3.6 beta release (The How-To Geek and Download Squad, for example). But I haven't seen this mentioned much since the official release of Firefox 3.6 a few days ago, so here's an update and a quick tutorial for those who bypassed the beta.

By default, Firefox shows a single thumbnail when you hover the mouse pointer over its icon in the Windows 7 taskbar with Aero enabled. Here's what it looks like:

The problem is, this particular Firefox window actually contains four open tabs, and it could contain dozens. It sort of defeats the purpose of the Aero preview feature if you have to open a window before you can scan which browser tabs you have open. IE8 does it right, showing all open tabs in thumbnail previews when you point to its icon. So how do you add the same feature to Firefox 3.6? Simple:

Open Firefox 3.6 (or later) and type about:config in the Location Bar. You'll have to click to get past this warning dialog box and open the Preferences page. Use the Filter box (or just scroll down) to find browser.taskbar.previews.enable in the list of preferences. Note that by default it's set to false. Double-click to toggle the setting to true. The value in the Status column changes to user set and the entire entry turns bold to indicate it's been changed. It should look like this:

And now aim the mouse pointer at the taskbar again:

Every tab (even if those tabs are in separate windows) is now visible from the taskbar previews. You can change the focus to any tab temporarily by pointing at it, and you can close any tab from its thumbnail preview using the X in the upper right corner.

And yes, I can hear the question now. What about Chrome? How do I enable this feature? The short answer is, you don't. It's on the issues list at chromium.org. A note from brian [at] chromium.org when the issue was fdirst opened, nearly a year ago (post date February 24, 2009), suggests, "[I]t is something we'd like to prioritize based on the adoption of Windows 7…" But there's no sign that it's actually under development. Too bad.