Tray Icon Change
This is a great event to add to most of your alerts. It's helpful to be able to see if there's an alert condition under way, and a quick glance at the tray can let you know by using the event.
The Tray Icon Change notification will do one or both of the following:
Change default icon to red during alert conditions
If you already have PingPlotter showing in the tray, this will change the existing green icon and add red to indicate that an alert has fired. If you don't have PingPlotter in the tray already, then a red icon will be added to the tray. When the alert condition(s) are over, the icon will change back to blue.
Popup message in tray
This shows a "balloon" message coming out of the tray. Not all versions of Windows support this message (ie: some versions of Windows 95), in which case no balloon will show. Only one balloon can be shown at a time, so the newest balloon always wins (a new balloon message will replace an older one).