This plugin doesn't work on Google Chrome since september 2013
On Firefox, the solution is to use this addon : https://addons.mozilla.org/fr/firefox/addon/html-notifications/
But since Firefox 22 (june, 24th, 2013), there is a native Firefox support notification and this addon no longer works at all.
Google Chrome: new API Notifications
I will soon propose a pull request which use window.webkitNotifications.createNotification(picture, title, text);
But the notification will be less beautiful than before because we can do fewer things. My solution will works with lastest Google Chrome and Firefox.