The diamond next to a running application in the Application menu indicates that the program has a message or an alert to display. The Notification Manager lets processes running in the background notify the user of messages or alerts without disrupting the process running in the foreground.
An example of an application that uses the Notification Manager is PrintMonitor. Rather than PrintMonitor taking control of the screen and becoming the active application, PrintMonitor alternates its icon with the Apple icon in the menu bar when it requires the user's attention. In addition, a small diamond is placed next to the application name in the Application menu.
The Notification Manager provides three alert levels:
- Polite: A blinking icon appears in the menu bar.
- Audible: The system beeps once.
- Alert Box: A dialog appears that the user must acknowledge.