Autohide Tabbar is a Firefox extension that auto-hides the tab bar. By moving the mouse to the edge of where the tab bar was, you can make the tab bar show up again.

Right click on the tab bar, you can see a menu item of "Autohide Tabbar". Use it to toggle the feature on or off. You can also toggle this feature by the extension's Options page -- accessed from Tools|Add-ons|Extensions|Autohide Tabbar|Options.

Requirements:
* Firefox
* Thunderbird

The license of this software is Free Trial Software, you can free download and get a free trial.