The Gnome Desktop

GNOME (pronounced guh-nome) provides the desktop environment that you get by default when you install Fedora, Ubuntu, and other Linux systems. This desktop environment provides the software that is between your X Window System framework and the look-and-feel provided by the window manager. GNOME is a stable and reliable desktop environment, with a few cool features.

As of this writing, GNOME 2.26 is the most recent version available, although the distribution you are using may or may not include this latest version. Recent GNOME releases include advancements in 3D effects (see "3D effects with AIGLX" later in this chapter), improved usability features, and an application for using your Webcam.

To use your GNOME desktop, you should become familiar with the following components:

• Metacity (window manager)—The default window manager for GNOME in Ubuntu, Fedora, RHEL, and others is Metacity. Metacity configuration options let you control such things as themes, window borders, and controls used on your desktop.

Compiz (window manager)—You can enable this window manager in GNOME to provide 3D desktop effects.

• Nautilus (file manager/graphical shell)—When you open a folder (by double-clicking the Home icon on your desktop, for example), the Nautilus window opens and displays the contents of the selected folder. Nautilus can also display other types of content, such as shared folders from Windows computers on the network (using SMB).

• GNOME panels (application/task launcher)—These panels, which line the top and bottom of your screen, are designed to make it convenient for you to launch the applications you use, manage running applications, and work with multiple virtual desktops. By default, the top panel contains menu buttons (Applications, Places, and System), desktop application launchers (Evolution e-mail and Firefox Web browser), a workspace switcher (for managing four virtual desktops), and a clock. Icons appear in the panel when you need software updates or SELinux detects a problem. The bottom panel has a Show Desktop button, window lists, a trashcan and workspace switcher.

• Desktop area—The windows and icons you use are arranged on the desktop area, which supports drag-and-drop between applications, a desktop menu (right-click to see it), and icons for launching applications. A Computer icon consolidates CD drives, floppy drives, the file system, and shared network resources in one place.

Here are some feature additions you will find useful in the most recent versions of GNOME:

• XSPF playlists in Totem—The Totem video/audio player now includes support for open standard XSPF playlists ( Other improvements to Totem allow it to interact with content from Web sites.

• Screensaver previews—Previewing screen savers in full-screen mode is now supported.

• Direct DVD burning—Use the Nautilus CD burner feature to burn DVDs directly, without needing first to create an ISO image.

• Drag from taskbar—Drag an application from the taskbar to workspaces represented in the panel Workspace Switcher to move the application to a new workspace.

• Nautilus text or button browsing—When saving or opening files or folders in Nautilus, a new toggle button enables you to choose between browsing by clicking on buttons or by typing full pathnames.

GNOME also includes a set of Preferences windows that enable you to configure different aspects of your desktop. You can change backgrounds, colors, fonts, keyboard shortcuts, and other features related to the look and behavior of the desktop. Figure 3-7 shows how the GNOME desktop environment appears the first time you log in, with a few windows added to the screen.


The GNOME desktop environment


The GNOME desktop environment

The desktop shown in Figure 3-7 is for Ubuntu. The following sections provide details on using the GNOME desktop.

Using the Metacity window manager

The Metacity window manager seems to have been chosen as the default window manager for GNOME because of its simplicity. The creator of Metacity refers to it as a "boring window manager for the adult in you"—and then goes on to compare other window managers to colorful, sugary cereal, whereas Metacity is characterized as Cheerios.


To use 3D effects, your best solution is to use the Compiz window manager, described later in this chapter. ■

There really isn't much you can do with Metacity (except get your work done efficiently). You assign new themes to Metacity and change colors and window decorations through the GNOME preferences (described later). A few Metacity themes exist, but expect the number to grow.

Basic Metacity functions that might interest you are keyboard shortcuts and the workspace switcher. Table 3-4 shows keyboard shortcuts to get around the Metacity window manager.


Metacity Keyboard Shortcuts



Window focus

Cycle forward, with pop-up icons


Cycle backward, with pop-up icons


Cycle forward, without pop-up icons


Cycle backward, without pop-up icons


Panel focus

Cycle forward among panels


Cycle backward among panels


Workspace focus

Move to workspace to the right

Ctrl+Alt+right arrow

Move to workspace to the left

Ctrl+Alt+left arrow

Move to upper workspace

Ctrl+Alt+up arrow

Move to lower workspace

Ctrl+Alt+down arrow

Minimize/maximize all windows


Show window menu


Close menu


Another Metacity feature of interest is the workspace switcher. Four virtual workspaces appear in the workspace switcher on the GNOME panel. You can do the following with the Workspace Switcher:

• Choose current workspace—Four virtual workspaces appear in the Workspace Switcher. Click any of the four virtual workspaces to make it your current workspace.

• Move windows to other workspaces—Click any window, each represented by a tiny rectangle in a workspace, to drag-and-drop it to another workspace. Likewise, you can drag an application from the Window List to move that application to another workspace.

• Add more workspaces—Right-click the Workspace Switcher, and select Preferences. You can add workspaces (up to 32).

• Name workspaces—Right-click the Workspace Switcher and select Preferences. Click in the Workspaces pane to change names of workspaces to any names you choose.

You can view and change information about Metacity controls and settings using the gconf-editor window (type gconf-editor from a Terminal window). As the window says, it is not the recommended way of changing preferences, so when possible, you should change the desktop through GNOME preferences. However, gconf-editor is a good way to see descriptions of each Metacity feature.

From the gconf-editor window, select apps C metacity, and then choose from general, global_ keybindings, keybindings_commands, window_keybindings, and workspace_names. Click each key to see its value, along with short and long descriptions of the key.

Using the GNOME panels

The GNOME panels are placed on the top and bottom of the GNOME desktop. From those panels you can start applications (from buttons or menus), see what programs are active, and monitor how your system is running. There are also many ways to change the top and bottom panels—by adding applications or monitors or by changing the placement or behavior of the panel, for example.

Right-click any open space on either panel to see the Panel menu. Figure 3-8 shows the Panel menu on the top.


The GNOME Panel menu

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About Panels

From GNOME's Panel menu, you can choose from a variety of functions, including:

• Use the menus—The Applications menu displays most of the applications and system tools you will use from the desktop. The Places menu lets you select places to go, such as the Desktop folder, home folder, removable media, or network locations. The System menu lets you change preferences and system settings, as well as get other information about GNOME.

• Add to Panel—Add an applet, menu, launcher, drawer, or button.

• Properties—Change the panel's position, size, and background properties.

• Delete This Panel—Delete the current panel.

• New Panel—Add panels to your desktop in different styles and locations.

You can also work with items on a panel. For example, you can

• Move items—To move an item on a panel, right-click it, select Move, and then drag-and-drop it to a new position.

• Resize items—You can resize some elements, such as the Window List, by clicking an edge and dragging it to the new size.

• Use the Window List—Tasks running on the desktop appear in the Window List area. Click a task to minimize or maximize it.

The following sections describe some things you can do with the GNOME panel.

Using the Applications and System menus

Click Applications on the panel, and you see categories of applications and system tools that you can select. Click the application you want to launch. To add an item from a menu so that it can launch from the panel, drag-and-drop the item you want to the panel.

You can add items to your GNOME menus. To do that, right-click on any of the menu names, and then select Edit Menus. The window that appears lets you add or delete menus associated with the Applications and System menus. You can also add items to launch from those menus by selecting New Item and typing the Name, Command, and comment for the item.

Adding an applet

You can run several small applications, called applets, directly on the GNOME panel. These applications can show information you may want to see on an ongoing basis or may just provide some amusement. To see what applets are available and to add applets that you want to your panel, perform the following steps:

1. Right-click an open space in the panel so that the Panel menu appears.

2. Select Add to Panel. An Add to Panel window appears.

3. Select from among several dozen applets, including a clock, dictionary lookup, stock ticker, and weather report. The applet you select appears on the panel, ready for you to use.

Figure 3-9 shows (from left to right) eyes, system monitor, weather report, network monitor, and wanda the fish.


Placing applets on the panel makes accessing them easy.

After an applet is installed, right-click it on the panel to see what options are available. For example, select Preferences for the stock ticker, and you can add or delete stocks whose prices you want to monitor. If you don't like the applet's location, right-click it, click Move, slide the mouse until the applet is where you want it (even to another panel), and click to set its location.

If you no longer want an applet to appear on the panel, right-click it, and then click Remove From Panel. The icon representing the applet disappears. If you find that you have run out of room on your panel, you can add a new panel to another part of the screen, as described in the next section.

Adding another panel

You can have several panels on your GNOME desktop. You can add panels that run along the entire bottom, top, or side of the screen. To add a panel, do the following:

1. Right-click an open space in the panel so that the Panel menu appears.

2. Select New Panel. A new panel appears on the side of the screen.

3. Right-click an open space in the new panel and select Properties.

4. From the Panel Properties, select where you want the panel from the Orientation box (Top, Bottom, Left, or Right).

After you've added a panel, you can add applets or application launchers to it as you did to the default panel. To remove a panel, right-click it and select Delete This Panel.

Adding an application launcher

Icons on your panel represent a Web browser and several office productivity applications. You can add your own icons to launch applications from the panel as well. To add a new application launcher to the panel, do the following:

1. Right-click in an open space on the panel.

2. Select Add to Panel C Application Launcher from the menu. All application categories from your Applications and System menus appear.

3. Select the arrow next to the category of application you want, and then select Add. An icon representing the application appears on the panel.

To launch the application you just added, simply click the icon on the panel.

If the application you want to launch is not on one of your menus, you can build a launcher yourself as follows:

1. Right-click in an open space on the panel.

2. Select Add to Panel C Custom Application Launcher C Add. The Create Launcher window appears.

3. Provide the following information for the application that you want to add:

• Type—Select Application (to launch a regular GUI application) or Application in Terminal. Use Application in Terminal if the application is a character-based or ncurses application. (Applications written using the ncurses library run in a Terminal window but offer screen-oriented mouse and keyboard controls.)

• Name—A name to identify the application (this appears in the tooltip when your mouse is over the icon).

• Command—The command line that is run when the application is launched. Use the full path name, plus any required options.

• Comment—A comment describing the application. It also appears when you later move your mouse over the launcher.

4. Click the Icon box (it might say No Icon). Select one of the icons shown and click OK. Alternatively, you can browse your file system to choose an icon.

5. Click OK.

The application icon should now appear in the panel. Click it to start the application.


Icons available to represent your application are contained in the / usr/share/pixmaps directory. These icons are either in .png or .xpm formats. If there isn't an icon in the directory you want to use, create your own (in one of those two formats) and assign it to the application. ■

Adding a drawer

A drawer is an icon that you can click to display other icons representing menus, applets, and launchers; it behaves just like a panel. Essentially, any item you can add to a panel you can add to a drawer. By adding a drawer to your GNOME panel, you can include several applets and launchers that together take up the space of only one icon. Click on the drawer to show the applets and launchers as if they were being pulled out of a drawer icon on the panel.

To add a drawer to your panel, right-click the panel and select Add to Panel C Drawer. A drawer appears on the panel. Right-click it, and add applets or launchers to it as you would to a panel. Click the icon again to retract the drawer.

Figure 3-10 shows a portion of the panel with an open drawer that includes an icon for launching a volume monitor, a weather report, and Tomboy sticky notes.


Add launchers or applets to a drawer on your GNOME panel. _¿fj_

Changing panel properties

Those panel properties you can change are limited to the orientation, size, hiding policy, and background. To open the Panel Properties window that applies to a specific panel, right-click on an open space on the panel and choose Properties. The Panel Properties window that appears includes the following values:

• Orientation—Move the panel to different locations on the screen by clicking on a new position.

• Size—Select the size of your panel by choosing its height in pixels (48 pixels by default).

• Expand—Select this check box to have the panel expand to fill the entire side, or clear the check box to make the panel only as wide as the applets it contains.

• AutoHide—Select whether a panel is automatically hidden (appearing only when the mouse pointer is in the area).

• Show Hide buttons—Choose whether the Hide/Unhide buttons (with pixmap arrows on them) appear on the edges of the panel.

• Arrows on hide buttons—If you select Show Hide Buttons, you can choose to have arrows on those buttons.

• Background—From the Background tab, you can assign a color to the background of the panel, assign a pixmap image, or just leave the default (which is based on the current system theme). Click the Background Image check box if you want to select an image for the background, and then select an image, such as a tile from /usr/share/ backgrounds/tiles or other directory.

I usually turn on the AutoHide feature and turn off the Hide buttons. Using AutoHide gives you more desktop space to work with. When you move your mouse to the edge where the panel is, the panel pops up—so you don't need Hide buttons. ■

Using the Nautilus file manager

At one time, file managers did little more than let you run applications, create data files, and open folders. These days, as the information a user needs expands beyond the local system, file managers are expected to also display Web pages, access FTP sites, and play multimedia content. The Nautilus file manager, which is the default GNOME file manager, is an example of just such a file manager.

When you open the Nautilus file manager window (for example, by opening the Home icon or other folder on your desktop), you see the name of the location you are viewing (such as the folder name) and what that location contains (files, folders, and applications). Double-click a folder to open that folder in a new window.

Select your folder name in the lower-left corner of the window to see the file system hierarchy above the current folder. GNOME remembers whatever size, location, and other setting you had for the folder the last time you closed it and returns it to that state the next time you open it.

To see more controls, right-click a folder and select Browse Folder to open it. Icons on the toolbar of the Nautilus window let you move forward and back among the directories and Web sites you visit. To move up the directory structure, click the up arrow. If you prefer to type the path to the folder you want, instead of clicking icons, you can toggle between button and text-based location bars (click the paper and pencil icon next to the location buttons to change the view). Figure 3-11 is an example of the file manager window displaying the home directory of a user named chris in browse mode.


The Nautilus file manager enables you to move around the file system, open directories, launch applications, and open Samba folders.

To refresh the view of the folder, click the Reload button. The Home button takes you to your home page, and the Computer button lets you see the same type of information you would see from a My Computer icon on a Windows system (CD drive, floppy drive, hard disk file systems, and network folders).

Icons in Nautilus often indicate the type of data that a particular file contains. The contents or file extension of each file can determine which application is used to work with the file, or you can right-click an icon to open the file it represents with a particular application or viewer.

Here are some of the more interesting features of Nautilus:

• Sidebar—From the Browse Folder view described previously, select View C Side Pane to have a sidebar appear in the left column of the screen. From the sidebar, you can click a pull-down menu that represents different types of information you can select one at a time.

The Tree tab, for example, shows a tree view of the directory structure, so you can easily traverse your directories. The Notes tab lets you add notes that become associated with the current Directory or Web page, and the History tab displays a history of directories you have visited, enabling you to click those items to return to the sites they represent. There is also an Emblems tab that lets you drag-and-drop emblems on files or folders to indicate something about the file or folder (emblems include icons representing drafts, urgent, bug, and multimedia).

• Windows file and printer sharing—If your computer is connected to a LAN on which Windows computers are sharing files and printers, you can view those resources from Nautilus. Type smb: in the Open Location box (select File C Open Location to get there) to see available workgroups. Click a workgroup to see computers from that workgroup that are sharing files and printers. Figure 3-12 shows an example of a local Nautilus window displaying icons representing folders shared from a Window computer named bluestreak that is accessible on the local LAN. The shared folder from that computer is named My Doc Blue.


Display shared Windows file and printer servers (SMB) in Nautilus.

Display shared Windows file and printer servers (SMB) in Nautilus.

• MIME types and file types—To handle different types of content that may be encountered in the Nautilus window, you can set applications to respond based on MIME type and file type. With a folder displayed, right-click a file for which you want to assign an application. Click either Open With an Application or Open With a Viewer. If no application or viewer has been assigned for the file type, click Associate Application to be able to select an application. From the Add File Types window, you can add an application based on the file extension and MIME type representing the file.

• Drag-and-drop—You can use drag-and-drop within the Nautilus window, between the Nautilus and the desktop, or among multiple Nautilus windows. As other GNOME-compliant applications become available, they are expected to also support the drag-and-drop feature.

If you would like more information on the Nautilus file manager, visit the GNOME Web site (

3D effects with AIGLX

Several different initiatives have made strides in recent years to bring 3D desktop effects to Linux. Ubuntu and Fedora used AIGLX ( aiglx). The openSUSE project originally backed the Xgl approach ( Xgl ), but has recently also moved to supporting AIGLX.

The goal of the Accelerated Indirect GLX project (AIGLX) is to add 3D effects to everyday desktop systems. It does this by implementing OpenGL ( accelerated effects using the Mesa ( open source OpenGL implementation.

Currently, AIGLX supports a limited set of video cards and implements only a few 3D effects, but it does offer some insight into the eye candy that is in the works.

Direct rendering infrastructure (DRI) is required for most video cards supporting AIGLX. However, some NVidia cards that don't support DRI can be used, but they require that you get the closed source binary drivers made available from NVidia. Cards that are known to not work with AIGLX include ATI Rage 128 and Mach 64, Matrox G200 through G550, and 3DFX Voodoo 1 and 2.

If your video card was properly detected and configured, you may be able to simply turn on the Desktop Effects feature to see the effects that have been implemented so far. To turn on Desktop Effects, select System C Preferences C Look and Feel C Desktop Effects. When the Desktop Effects window appears, select Enable Desktop Effects. Enabling this does the following:

• Stops the current window manager and starts the Compiz window manager.

• Enables the Windows Wobble When Moved effect. With this effect on, when you grab the title bar of the window to move it, the window will wobble as it moves. Menus and other items that open on the desktop also wobble.

• Enables the Workspaces on a Cube effect. Drag a window from the desktop to the right or the left and the desktop will rotate like a cube, with each of your desktop workspaces appearing as a side of that cube. Drop the window on the workspace where you want it to go. You can also click on the Workspace Switcher applet in the bottom panel to rotate the cube to display different workspaces.

Other nice desktop effects result from using the Alt+Tab keys to tab among different running windows. As you press Alt+Tab, a thumbnail of each window scrolls across the screen as the window it represents is highlighted.

Figure 3-13 shows an example of a Compiz desktop with AIGLX enabled. The figure illustrates a Web browser window being moved from one workspace to another as those workspaces rotate on a cube.


Rotate workspaces on a cube with AIGLX desktop effects enabled.


Rotate workspaces on a cube with AIGLX desktop effects enabled.

The following are some interesting effects you can get with your 3D AIGLX desktop:

• Spin cube—Hold Ctrl+Alt keys and press the right and left arrow keys. The desktop cube spins to each successive workspace (forward or back).

• Slowly rotate cube—Hold the Ctrl+Alt keys, press and hold the left mouse button, and move the mouse around on the screen. The cube will move slowly with the mouse among the workspaces.

• Tab through windows—Hold the Alt key and press the Tab key. You will see reduced versions of all your windows in a strip in the middle of your screen, with the current window highlighted in the middle. Still holding the Alt key, press Tab or Shift+Tab to move forward or backwards through the windows. Release the keys when the one you want is highlighted.

• Scale and separate windows—If your desktop is cluttered, hold Ctrl+Alt and press the up arrow key. Windows will shrink down and separate on the desktop. Still holding Ctrl+Alt, use your arrow keys to highlight the window you want and release the keys to have that window come to the surface.

• Scale and separate workspaces—Hold Ctrl+Alt and press the down arrow key to see reduced images of the workspace shown on a strip. Still holding Ctrl+Alt, use right and left arrow keys to move among the different workspaces. Release the keys when the workspace you want is highlighted.

• Send current window to next workspace—Hold Ctrl+Alt+Shift keys together and press the left and right arrow keys. The current window will move to the next workspace to the left or right, respectively.

• Slide windows around—Press and hold the left mouse button, and then press the left, right, up, or down arrow keys to slide the current window around on the screen.

If you get tired of wobbling windows and spinning cubes, you can easily turn off the AIGLX 3D effects and return Metacity as the window manager. Select System C Preferences C Desktop Effects again and toggle off the Enable Desktop Effects button to turn off the feature.

If you have a supported video card, but find that you are not able to turn on the Desktop Effects, check that your X server started properly. In particular, make sure that your /etc/X11/xorg. conf file is properly configured. Make sure that dri and glx are loaded in the Module section. Also, add an extensions section anywhere in the file (typically at the end of the file) that appears as follows:

Section ""extensions"" Option ""Composite""


Another option is to add the following line to the /etc/X11/xorg.conf file in the Device section:

Option ""XAANoOffscreenPixmaps""

The XAANoOffscreenPixmaps option will improve performance. Check your / var/log/ Xorg.log file to make sure that DRI and AIGLX features were started correctly. The messages in that file can help you debug other problems as well.

Changing GNOME preferences

There are many ways to change the behavior, look, and feel of your GNOME desktop. You can modify most GNOME preferences from submenus on the Preferences menu (select System C Preferences).

Unlike earlier versions of GNOME, boundaries between preferences related to the window manager (Metacity), file manager (Nautilus), and the GNOME desktop itself have been blurred. Preferences for all of these features are available from the Preferences menu.

The following items highlight some of the preferences you might want to change:

• Accessibility—If you have difficulty operating a mouse or keyboard or seeing the screen, the Assistive Technologies window lets you adapt mouse and keyboard settings to make operating your computer easier for you. It also lets you magnify selected applications. (Select System C Preferences C Personal C Assistive Technologies.)

• Desktop Background—You can choose a solid color or an image to use as wallpaper. Select System C Preferences C Look and Feel C Appearance and then the Background tab. If you choose to use a solid color (by selecting No Wallpaper), click the Color box, select a color from the palette, and click OK.

To use wallpaper for your background, open the folder containing the image you want to use, and then drag the image into the Desktop Wallpaper pane on the Desktop Preferences window. You can choose from a variety of images in the /usr/share/nau-tilus/patterns and /usr/share/backgrounds/tiles directories. Then choose to have the wallpaper image tiled (repeated pattern), centered, scaled (in proportion), or stretched (using any proportion to fill the screen).

• Screensaver—Choose from dozens of screen savers from the Screensaver window. Select System C Preferences C Look and Feel C Screensaver. Choose Random to have your screen saver chosen randomly from available screen savers, or select one that you like from the list to use all the time. Next, choose how long your screen must be idle before the screen saver starts (default is 10 minutes). You can also choose to lock the screen when the screen saver is active, so a password is required to return to the desktop. If you only see a few screen savers, you might want to install the xscreensaver-extras and xscreensaver-gl-extras packages to get a bunch more.

• Theme—Choose an entire theme of elements to be used on your desktop, if you like. From the Appearance window, select the Theme tab. A desktop theme affects not only the background but also the way that many buttons and menu selections appear. Only a few themes are available for the window manager (Metacity) in the Fedora distribution, but you can get a bunch of other themes from (click Metacity).

To modify a theme, select the Customize button and then click the Controls tab to choose the type of controls to use on your desktop. Click the Window Border tab to select from different themes that change the title bar and other borders of your windows. Click the Icons tab to choose different icons to represent items on your desktop. Themes change immediately as you click or when you drag a theme name on the desktop.

Exiting GNOME

When you are done with your work, you can either log out from your current session or shut down your computer completely. To exit from GNOME, do the following:

1. Click the System button from the panel (in Fedora) or the red button icon in the upper-right corner (in Ubuntu).

2. Select Log Out from the menu. A pop-up window appears, asking whether you want to Log Out. Some versions will also ask whether you want to Shut Down or Restart the computer.

3. Select Log Out from the pop-up menu. This logs you out and returns you to either the graphical login screen or to your shell login prompt. (If you select Shut Down, the system shuts down, and if you select Reboot, the system restarts.)

4. Select OK to finish exiting from GNOME.

If you are unable to get to the Log Out button (if, for example, your panel crashed), two other exit methods are available. Try one of these ways, depending on how you started the desktop:

• If you started the desktop from the graphical display manager or by typing startx from your login shell, press Ctrl+Backspace to end your GNOME session.

• If your screen is completely unresponsive (mouse and keyboard aren't working), you might just have to reboot your computer. If possible, log in to the computer over the network and type init 6 (as root user) to reboot.

Although these ways are not the most graceful for exiting the desktop, they work. You should be able to log in again and restart the desktop.

Continue reading here: Configuring Your Own Desktop

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