6. Using the X Window System

Contents:
Keyboard Operations
Mouse Operations
Window Managers
Desktops
Using GNOME
Using GNOME Applets and Applications
Configuring GNOME

Using the X Window System means interacting with Linux on several different levels. X itself simply provides the graphics for displaying components of a graphical user interface: X draws the screen, draws objects on the screen, and tracks user input actions such as keyboard input and mouse operations. To organize all of this into familiar objects like windows, menus, and scrollbars, X relies on a separate program called a window manager. A window manager alone won't necessarily assure tight integration between applications running under X; that higher degree of integration comes from something called a desktop environment. While X itself is a single program, X under Linux supports several popular window managers, and two popular desktop environments.

To use X effectively, you'll learn the basic keyboard and mouse operations for communicating with X. If you're like most X users, you'll find it helpful to use a window manager and a desktop with X. You'll learn why window managers and desktops are useful and get help in choosing and setting up a window manager and a desktop.

6.1 Keyboard Operations

Using the keyboard with X closely resembles using the keyboard with Microsoft Windows. X sends your keyboard input to the active window, which is said to have the input focus. The active window is usually the window in which you most recently clicked the mouse; however, under some circumstances, it can be the window beneath the mouse cursor.

This chapter refers to your pointing device as a mouse. However, like Microsoft Windows, X supports a variety of pointing devices.

Microsoft Windows lets you choose to perform most operations by using the keyboard or mouse. In contrast, X was designed for use with amouse. If your mouse isn't functioning, you'll find it quite challenging or even impossible to use most X programs.

Similarly, X provides a few important functions that you can access only via the keyboard:

Using virtual consoles
Switching video modes

In addition, you can use the keyboard to terminate X.

6.1.1 Switching Video Modes

When you configured X, you specified the video modes in which X can operate. Recall that the current video mode determines the resolution and color depth of the image displayed by your monitor - for example 16 bits per pixel color depth and 1024×768 pixels screen resolution.

By pressing Shift-Alt-+ (using the plus key on the numeric keypad), you command X to switch to the next video mode in sequence. X treats the video modes as a cycle: If X is operating in the last video mode, this key sequence causes X to return to the first video mode.

The similar key sequence Shift-Alt-- (using the minus key on the numeric keypad) causes X to switch to the previous video model. If you shift to a video mode that your monitor doesn't support - as demonstrated by a unsteady or garbled image - you can use this key sequence to return to a supported video mode, avoiding the inconvenience of terminating X.

6.1.2 Using Virtual Consoles with X

Even while X is running, you can access the Linux virtual consoles. To switch from graphical mode to a virtual console running in text mode, type Ctrl-Alt-F n, where F n is a function key and n is the number of the desired virtual console. X uses virtual console 7, so only virtual consoles 1-6 are accessible while running X.

To switch from a virtual console back to X, type Alt-F7. Nothing is lost when you switch from X to a virtual console or back, so you can move freely between the graphical and text operating modes.

6.1.3 Terminating X

As you learned in the previous chapter, you can terminate X by typing Ctrl-Alt-Backspace. X immediately terminates each program running under X, closes each open window, and returns your system to text mode.

This key sequence terminates X abruptly; most window managers support gentler ways of terminating X. You'll learn about these later in this chapter.

While X is running, you cannot use the Ctrl-Alt-Del sequence to reboot your system. To reboot your system, you can terminate X and then use the Ctrl-Alt-Del sequence, or access a terminal window and enter the command:

 shutdown -r now

The shutdown command terminates X and then reboots your system.

6.1.4 Terminal Windows

In Windows, you need not restart in DOS mode simply to have access to the DOS command line. Similarly, in X you need not switch to a virtual console simply to have access to the command line. X enables you to open a terminal window. A terminal window resembles the familiar Microsoft Windows MS-DOS Prompt window; like the Linux shell, it lets you type commands and view command output. Various window managers support different ways of accessing a terminal window.

6.1.5 Pop-Up Menus

The terminal window is just one example of a frequently used program under X that you'll want to access. Most window managers install with a default set of common programs that can be accessed by left- or right-clicking with the mouse on the desktop. Most window managers, for example, let you click on the desktop and select a terminal window program from the pop-up menu that appears. However, the pop-up menu displayed by a window manager may display program names rather than program functions. In this case, you may have some difficulty determining which entry on the pop-up menu corresponds to a terminal program. Many programs that provide terminal windows have names that include the sequences xt or xterm. Selecting such an entry will probably launch a terminal window. You'll learn more about window managers and how to use them later in this chapter.