daemon to display passive popup notifications

 mate-notification-daemon displays passive popup notifications, as per
 the Desktop Notifications Specification.
 .
 The Desktop Notifications Specification provides a standard way of
 doing passive popup notifications on the Linux desktop. These are
 designed to notify the user of something without interrupting their
 work with a dialog box that they must close. Passive popups can
 automatically disappear after a short period of time, as per the
 Desktop Notifications spec.