If you are using a Mac computer and would like to utilize the desktop notification feature, you'll want to consider using Google Chrome.  Desktop notification extension for Firefox seems to have a bug and does not work on Mac Firefox browsers.  This is something with the actual desktop notification extension.  Once they fix the bug it should also work on the PHP Live! system.

The desktop notification for Firefox can be found at:

http://www.phplivesupport.com/r.php?r=dn_firefox