Firefox: ABOUT:CONFIG (Advanced)

Note: This is an advanced tip for the Firefox browser, and should only be performed by people who understand what they're doing. My modifying the wrong value you can prevent your browser from working until you restore it to the proper value.

If you really want to customize Firefox then you need to learn about its low-level configuration area known as ABOUT:CONFIG. This configuration area is the equivalent of the Windows Registry, it can be used for changing or fine-tuning different areas of the browser (such as the: user interface, network setting, or other aspects of the browser's behavior).

To access the ABOUT:CONFIG area:

• Open the Firefox browser.
  
• In the URL field, type "ABOUT:CONFIG" and press the Enter key.

Firefox will display a long list of preference settings sorted alphabetically. Each setting controls a different aspect of the browser's behavior. To change a setting's value double-click on it. If it's a boolean value then it will be toggled, otherwise a dialog will pop-up asking you to enter the appropriate information. Each setting can contain a value type of: integer, string, or boolean.

There is a great reference for all these preference settings, see the ABOUT:CONFIG FAQ.

Note: ABOUT:CONFIG uses data from the PREFS.JS file in your Firefox profile folder. You should backup this file before making any changes to the ABOUT:CONFIG area.