Note: We have briefly covered this before but present it here in a more detailed format.
Before
For our example we opened all of the websites in the HTG Network in tabs…
When hovering over the Firefox Icon in the Taskbar, you only see the one thumbnail. There are two things in particular to notice here:
1.) The Tab Bar for Firefox is displayed with all four tabs visible in the Thumbnail Preview
2.) The “Taskbar Icon” itself is displaying as singular with no “fanned edge” on the right side.
Hack the About:Config Settings
To get the Thumbnail Previews working you will need to make a modification in the about:config settings. Type about:config in the Address Bar and press Enter. Unless you have previously disabled the warning you will see this message after pressing Enter. Click on the I promise! Button to finish entering the settings.
In the Filter Address Bar either type or copy and paste the following about:config entry:
After you enter that in, you should see the entry listing as shown here. At this point there are two methods that you can choose to alter the entry. The first method is to right click on the entry and select Toggle and the second method is to double click on the entry. Both work equally well…choose the method that you like best.
Once the about:config entry has been changed, you will need to restart Firefox for it to take effect.
After restarting Firefox on our system the Thumbnail Previews were definitely looking very nice. Notice that the Tab Bar is no longer displayed in the Thumbnail Previews.
The Taskbar Icon also had a “fanned edge” indicating that multiple tabs were open.
Conclusion
If you are tired of waiting for Mozilla to officially activate Taskbar Thumbnail Previews in Firefox, then you can go ahead and start enjoying them now. For more great Firefox 3.6.x about:config hacks read our article here.
