pref("general.config.filename", "mozilla.cfg");
pref("general.config.obscure_value", 0);

defaultPref();	// set new default value
pref();		// set pref, allow changes in current session
lockPref();	// lock pref, disallow changes

That would help against opening the about:preferences page in a tab like is possible in current Firefox versions. If you only want to prevent users from changing specific settings then you can consider to lock involved prefs. ----- You can use a mozilla.cfg file in the Firefox program folder to lock prefs or specify new (default) values. Place a local-settings.js file in the defaults\pref folder where also the channel-prefs.js file is located to specify using mozilla.cfg. pref("general.config.filename", "mozilla.cfg"); pref("general.config.obscure_value", 0); These functions can be used in the mozilla.cfg file: defaultPref(); // set new default value pref(); // set pref, allow changes in current session lockPref(); // lock pref, disallow changes See: *http://kb.mozillazine.org/Locking_preferences *http://mike.kaply.com/2012/03/16/customizing-firefox-autoconfig-files/ *http://mike.kaply.com/2014/01/08/can-firefox-do-this/