If you have upgraded the Firefox web browser to version 21, the most recent version at the time of writing, you may have noticed that it is missing the All Tabs preview feature that was included in previous versions of the browser. It displayed a button in the web browser that you could click on to display an overlay window displaying all open tabs of the browser as thumbnail previews. It furthe
![Restore Firefox's All Tabs preview feature - gHacks Tech News](https://cdn-ak-scissors.b.st-hatena.com/image/square/69d5a753c05aa62b88d6530ac034058fc1fef97d/height=288;version=1;width=512/https%3A%2F%2Fwww.ghacks.net%2Fwp-content%2Fuploads%2F2013%2F05%2Ffirefox-alt-tab.jpg)