GNOME Shell Desktop, Panel, And Notifications
The empty GNOME 3 Shell contains three main elements: the panel, desktop, and notifications. In GNOME-speak, that's the Panel, Windowing Area, and Messaging Tray.
|The Desktop, Or Windowing Area|
Although you see wallpaper, it's simply a backdrop. No files, folders, shortcuts, or widgets appear on the GNOME 3 desktop. No file management functions or organization can occur on the GNOME 3 desktop. It is nothing more than wallpaper and an area for windows to populate.
While GNOME 3 is not the first GUI to do away with the conventional desktop, it may be the most strict in its implementation. KDE 4 made this move earlier. However, KDE 4 has the Folder View Plasmoid, which shows the contents of the Desktop folder within a widget. GNOME 3 has no comparable feature.
GNOME 3's panel resides along the upper edge of the screen. While it may look similar, the GNOME 3 panel significantly differs from the upper panel in GNOME 2. The GNOME 3 panel consists of five major parts: the Activities button, focused application icon/name, clock, system status indicators, and the user menu. Let's go over the changes from left to right.
First up, on the far-left edge of the panel, is the Activities button. This replaces the Applications/Places/System menu in GNOME 2. Pressing the Activities button or moving the pointer to the upper-left corner of the screen activates the Overview, both of which are explained in detail on the next page.
The empty space directly to the right of the Activities button is reserved for the icon and name of the foreground application. In the future, this icon will double as the application's menu bar, presumably in drop-down form.
In GNOME 2, the clock was on the right side of the upper panel with the rest of the indicators. In GNOME 3, the clock shifts to the middle of the Panel. Click the clock to reveal a pop-out calendar. Integration with the Evolution personal information manager displays any upcoming appointments in the calendar.
System Status Indicators
There is new differentiation between system status indicators and application-specific indicators/notifications in GNOME 3. Only system-level indicators appear in the panel, while application-specific indicators and notifications are now housed in an auto-hide bar at the bottom of the screen called the Messaging Tray (explained later). The system status indicators remain on the right side of the GNOME 3 panel, and just like we saw in Ubuntu, left- and right-clicking yields the exact same menu. The ability to reorganize or add additional applets is gone, too. System status indicators include: Universal Access, Volume, Bluetooth, Network, Wi-Fi, and Battery Life indicators.
The user menu at the far right end of the panel hosts messaging status, a switch to enable/disable notification, Online Accounts, System Settings, Lock Screen, Switch User, Log Out, and Suspend functions. Upon first inspection, it appears that in order to restart or shut down the system, you must first log out to the log-in screen and shut down or restart from there. However, a more convenient (yet totally not obvious) method also exists. Holding down one of the Alt keys while the user menu is open changes the Suspend option to Power Off.
Selecting Power Off brings up the choice to Restart or Power Off (shut down).
Also located in the user menu is a unified categorical listing of system tools, much like what you'd find in Windows, Mac OS X, KDE, and Unity. The System Settings menu replaces the alphabetically-listed System drop-down in GNOME 2's Applications/Places/System menu.
|Notifications Area, Or Messaging Tray|
Application-level indicators and notifications are now found at the bottom of the screen. Moving the cursor to the lower right-hand corner brings up the new Notification Area/Messaging Tray. Notification area icons for messaging applications like Skype and Pidgin are now found here. If you are using Empathy, the default chat client, messaging is even accessible within pop-ups from the tray. There's no need to switch to the actual application window.
Non-messaging applications also use the messaging tray for notifications. For example, Rhythmbox play controls, Firefox downloads, and device status now appear in the Messaging Tray.