Firefox's addon bar can be tremendously useful, but for those of us who like our screen real estate, we'd prefer it stay out of the way.
The addon bar was implemented to house a number of icons, including those for both built-in functions and addons. Most addons put their own icon in the top of the Firefox window, beside the navigation bar. One of the great things about Firefox, though, and a huge draw for power users, is the customizability of the entire Firefox interface. If you'd prefer to put those icons somewhere else - anywhere else - you can. Ideally, though, you could still retain quick access. That's where this addon comes in.
Right-click somewhere on the navbar and click "customize," and drag all those icons to your addon bar at the bottom of the window. Then install this userstyle. (If you haven't already, you'll need to install Stylish.) Now, when you don't need it, the addon bar will disappear. When you need it, just hover your mouse somewhere near the bottom of the window, and it will reappear. By default, it will disappear in four seconds. If you'd like to change that, just edit this line in the code:
-moz-transition-delay: 4s !important;/* determines how long the Add-on bar waits to before hiding */
... and change "4s" to "10s" for a ten-second delay, for example. It's a tiny bit of real estate, but it can make a big difference:
If this userstyle appeals to you, you may want to check out the rest from creator rob64rock, who's created a ridiculous amount of userstyles for Firefox.
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