Firefox already has a Full Screen feature, which you can access by going to View -> Full Screen, or by pressing F11.
However, the standard Firefox full screen view still includes a location/toolbar and a tab bar, if you have any tabs open.
Fullerscreen is an extension that gives Web pages in Firefox the full run of your monitor. If you spend much time using Web-based applications like Gmail, Google Notebook, or Backpack, Fullerscreen is a must-have addition to Firefox.
Firefox's F11 fullscreen after Fullerscreen installation:
The Fullerscreen extension extends the Web page from top to bottom and to both sides of the screen. The only intrusion by browser chrome is the scrollbar, if the page requires scrolling.
To get the extension go to Firefox's Add-ons site, click the Install button and Firefox will walk you through the installation process. Once Fullerscreen is installed, you'll need to restart Firefox. Then, open the Add-ons manager by going to Tools -> Add-ons and select Fullerscreen. Click Preferences to modify Fullerscreen's behavior.
In the preference dialog, you can tweak Fullerscreen's behavior — how close the mouse gets to the edge of the screen before Fullerscreen displays the toolbar, whether you'll see updates to the status bar, and how long the toolbar should be displayed.
You can turn off the status bar updates if you don't care about the messages displayed there, and if it's left on, the status bar will be displayed almost constantly when viewing some sites, such as Gmail.
You can also get to the preferences dialog by going to the status bar and right-clicking on the Fullerscreen icon, which is a square with four arrows pointing at the corners of the square.
After you've set the preferences, close the Add-ons manager, go to a Web page you want to see full screen, and press F11 or click the Fullerscreen icon on the status bar. At this point, you should have nothing but Web page staring you in the face.
If you want to enter a URL, type CTRL-L. Instead of bringing the cursor to the location bar, Fullerscreen will open the Open Web Location dialog. If you want to search, type CTRL-K, which will take you to Firefox's default search engine.
