The GNOME desktop features a status notification area that the user can add to any panel on their desktop. This area is reserved for notifying the user of non-critical, application-related events (for example, arrival of new email, or a chat 'buddy' having logged on), and for monitoring the status of system tasks (for example, network or printer activity, or laptop battery charging).
Following the guidelines in this section will help to clarify the difference in the user's mind between information presented in the notification area, and controls and information presented on other parts of the panel.
Possible rule of thumb: you should probably write an applet instead of using the notification area if:
clicking your notification area icon does anything other than opening a window directly associated with the icon (e.g. a mail folder window for a new mail icon, or a print queue window for printer notification icon), or
there are icon-specific options on its context menu for doing anything other than that
your application would ever need to display more than one notification icon at the same time
Guidelines
Use table perspective for icons representing physical devices, with the light source above and to the left of the represented object. For example, a printer icon during printing. See the section called “Perspective” for more about table perspective.
Use shelf perspective, with overhead lighting, for all other icons. For example, an envelope shown when new mail arrives. See the section called “Perspective” for more about shelf perspective.
Use flat images for perpetual displays that change over time, such as load meters. Clearly delimit the boundaries of flat images. For example, a load meter which which displays a scrolling green bar graph on a black background should have a one black pixel border.
The utility of the notification area decreases rapidly when more than about four(?) icons are always present.
Guidelines
Only core GNOME programs may perpetually display an icon or use flat images.
Non-core programs for which a perpetual icon may be useful must default to not perpetually showing the icon. They may present an option to do so, however. Standard way of presenting this option would be nice.
Henceforth "icon" means an icon or a flat image.
Guidelines
Icons should not usually appear animated. The may change to indicate a change of state, but should not do so when that change is occurs regularly rapidly. A battery status indicator would usually change slowly, therefore an icon is appropriate. By contrast, a load meter would always be changing, therefore it should use a flat image.
Icons are permitted to blink under a few conditions. An icon may blink for n (=5?) seconds when first displayed if showing the icon is not caused by user action. A printing-in-progress icon would be shown because the user is printing a document, therefore it should not blink. An incoming email or personal message (IM) would be shown because something has changed absent the user, therefore it may blink.
A icon may blink for n seconds if its conditions for initially blinking recur. For example, an incoming email icon which was shown and blinked when a message arrived and which has remained visible may blink again when another message arrives.
Any icon may blink to indicate an error in deference to showing an alert. For example, a printing-in-progress icon may blink when there is a paper jam, but not when the printer is on fire - that should show an alert.
Do not rely on blinking or animation as a means of alerting the user to any particular event. The notification area respects the global desktop "no animation" preference for accessibility reasons. Note: This doesn't exist yet but it's on the list...
Icons should respond to the these user actions. (Keypresses apply only when the icon has focus, of course)
Guidelines
Double-click or Space key should perform the icon's default action. Normally this should open a window with relevant data, for example:
the printer queue for a printing-in-progress icon.
the inbox for an incoming email iconi
the message for an incoming message
Right-click or Shift-F10 should present a menu for the icon containing at least the icon's default action.
If the icon's properties may be altered, it should have a menu item
in its menu, nd show its property panel in response to Alt+Enter.Icons should obey normal tooltip conventions.