Because Mozilla changed Firefox, X-Notifier 4.x doesn't have the ability to use custom scripts anymore. We can only choose from the menu in X-Notifier's "Options". But for the time being, you can still use X-N 3.5.23, if you turn off automatic updates in FireFox: Tools, Addons, find X-Notifier, click 'More', scroll down to 'Automatic Updates', select 'Off' ...and you'll stay on the current version. If you want to reinstall 3.5.23, you can redownload it from https://addons.mozilla.org/en-us/firefox/addon/4490/versions
Read what I wrote other forum
http://xnotifier.tobwithu.com/dp/comment/11451#comment-11451
X-Notifier 4.02, no custom scripts
Because Mozilla changed Firefox, X-Notifier 4.x doesn't have the ability to use custom scripts anymore. We can only choose from the menu in X-Notifier's "Options".
But for the time being, you can still use X-N 3.5.23, if you turn off automatic updates in FireFox: Tools, Addons, find X-Notifier, click 'More', scroll down to 'Automatic Updates', select 'Off' ...and you'll stay on the current version. If you want to reinstall 3.5.23, you can redownload it from https://addons.mozilla.org/en-us/firefox/addon/4490/versions
Script into extention
Is it possible to convert scripts into separate extentions? These extentions should be extremly simple, so conversion should be automated.
X-Notifier can check for such extentions and use additional functionality if present.