How to automatically set preferences, such as those in "about:config", while Firefox running? Can I do that via javascript or something? I tried script in Greasemonkey: user_pref("network.protocol-handler.expose.file", false); but it doesn't work - probably because user_pref is not a javascript function. I need that because Firefox deletes my preferences, see: https://support.mozilla.org/en-US/questions/1005413 ''please stick with your original thread - no point in creating a new thread every time you post something about this issue - moderator''