Firefox about:config is the hub for all the advanced settings and preferences. Not everyone is comfortable making changes to the configuration files. This is where the Firefox lovers actually need a way around to do away with advanced preferences and settings. Gui:config provides the smart solution for altering the advanced settings and Firefox preferences (similar to Opera preference settings).
Gui:config simplifies the task of setting the user preferences by providing a simple and easy to use graphical interface. The interface provides check boxes, drop-down lists and text boxes for configuring the required settings (as you get in “Options” window).
After you install the add-on, you will observe the menu-item named “Advanced Settings” in the “Tools” menu. Click on the “Advanced Settings” and make your way through essential adjustments with this new and elegant way of making settings at about:config.