Notifications

Notifications are the way for both the applications and the system itself to indicate when an event happens which the user should be notified of, or to indicate a persistent state.

Structure

A notification is made of:

  • A title
  • A description

As well as optional fields:

  • A description
  • An icon (by default the icon of the application)
  • A notification sound (by default selected by the system)
  • A shaking effect
  • A background color (by default chosen by the desktop environment)
  • A set of buttons
  • A cover image
  • A persistent state
  • A type-dependent set of data
  • A timeout
  • A handler called when the notification is clicked
  • A context menu when the notification is right-clicked

Display rules

The way notifications are displayed depends on the desktop environment, therefore the requested shaking effect, background color, and so on may not be respected by the DE, although it's highly recommanded for a DE to follow these attributes.

Also, there is no rule indicating how elements are visually arranged inside a notification. Some DE may for instance put the icon on the left, while some others on the right. Additional elements may also be displayed, such as a cross to close the notification or an arrow to hide it to the notifications center.

Cover image

A notification can request to display a large image. Some desktop environments may decide to hide the application's icon in such case.

Buttons

Notifications can have action buttons, which are then linked to the owner application's event system. Buttons are usually limited in size and colors.

Persistent notifications

Persistent notifications don't disappear after a timeout. They can for instance be used to indicate a continuous state like the progress of a task.

Notification types

There are several notification types, which their own required sets of data.

Free notifications

This is the default type of notifications, which has no particular constraint.

Multimedia notifications

Multimedia notifications are used to indicate a multimedia playback. It must be composed of a cover image and six buttons (previous, rewind, play/pause, stop, fast-forward, next) whose appearance is decided by the desktop environment.

They are always persistent, and disappear when the playback stops completely.