An empty message tray is indicated by a dimmed indicator in the upper right panel. The indicator consists of a colored field and an icon. The field is used to highlight a count of the notification sources in the tray. The icon indicates a chat source or a regular message source.

If a notification is received and has a "chat" source the blue field is changed to red and the icon is changed to the default chat avatar. If multiple chat sources are in the message tray the extension indicator field will remain red until all chat sources are handled (ie. opened).

The count displayed by the extension is a count of notification sources. An application can send multiple notifications to a single source. The extension will count the source as one but in the message tray the count on the icon displayed is the number of notifications associated with the source. A source can be a Message Tray Source or a Telepathy Client Chat Source. This extension uses the default chat avatar if there is at least one chat source in the tray. If there is at least one unhandled chat message then the field is red. The count of two here could mean one Chat Source with an unhandled message and one Message Tray source or the count of two could indicate two Chat Sources one of which (or both) have an unhandled message.

The extension indicates a single non-chat source.

The icon in the tray has no count. A Message Tray Source displays a count only if the source represents more than one notification.

The extension indicates two non-chat sources.

In the tray Henry is a non-chat source with one notification. Henry is wearing a blue contact lens.

In the tray Moby is a non-chat source with four notifications.

The extension indicates three sources in the tray.

... a notification of a mounted removable device. Note the extension flags chat sources with an unhandled message by using a red count in the tray.

... Moby has four notifications.

... bogwan's chat message has not been handled. A Telepathy Client Chat Source displays a count until it is handled.

... bogwan's chat message was handled. The extension icon remains the chat avatar.

... bogwan no longer has a count in the tray.

The bogwan chat source is removed from the tray when the chat application is closed, The extension changes the indication to two non-chat Message Tray sources.

... only Moby and the device are in the tray.

When notifications are turned OFF, this extension continues to function.

This extension will work sanely with Empathy which interfaces correctly with the Telepathy Client. Other chat application notifications are not identified as a chat if they do not create the Telepathy Client Chat Source and interface with it properly.

Other extensions which alter the Message Tray or Telepathy Client can adversely affect this extension. There is no dependency apparatus ( or is one reasonably possible ) that can coordinate monkey patching.