The Firefox addon gui:config is one of the most useful addon I have ever come across. This addon makes available dozens of options, accessible only through “about:config”, to the common user by bringing these in a friendly graphical interface. So instead of tackling those cryptic lines in “about:config”, all you have to do is click buttons, checkboxes and drop down menus. You still can’t access a large number of “about:config” options through the GUI but the most common and important ones are included.
After installing this addon, these advanced options can be reached from Tools> Advanced Settings. The best part is: this tool explains every option found on the settings window. Simply hover the mouse over a setting and read the information box at the bottom. gui:config is equally useful and helpful to both novice and seasoned users.
I have included plenty of screenshots to show you some of the options that are available through this tool.