Using X Windows

The look and feel of X Windows is mostly the responsibility of the particular window-manager you’ve chosen to run. (You can learn more about window managers and some of their options later in this lesson.) You’ll find that there are a number of constants between the various managers. Some of these consistent features might be familiar to anyone who has previously used a computer with a mouse. A few, however, are likely to be new even to users familiar with the Macintosh and MS-Windows environments. The significant things to remember are:

•  X is designed for a three-button mouse—Most X software makes use of the left button for pointing, clicking, and selection. X uses the center button for general functions such as moving or resizing windows, and the right button for application-specific functions such as opening in-application pop-up menus. Of course, any application is capable of modifying these uses, so examination of the documentation is always appropriate.

•  X has the concept of focused input—On the Macintosh or MS-Windows platforms, if you type on the keyboard you generally expect the typing to appear in whatever window or dialog box is active—this isn’t the case with X Windows. In X, the window manager has the option of focusing your input anywhere it chooses. Most window managers can be configured to either focus input on the foremost window, focus input on a selected window (X does not have to be the foremost window), or focus input on whichever window the cursor is over. The last option, although unlike the interface you might be familiar with, is usually considered to be the most powerful. With the window manager configured so that focus follows the cursor, you can direct typing into a mostly hidden window—for example, to start a non-interactive program—by simply moving the cursor over any visible part of the mostly-hidden window and typing. No need to waste time bringing that window to the front, typing the command, and then shuffling the window back underneath the window that you really wanted to be working in.

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Caution:  
If Your Input Disappears  If you’re typing and you notice that what you’re typing isn’t appearing where you think it is supposed be, chances are you’ve got your input focused in some other window. Check to make certain that your cursor is where it belongs, or—if your system is configured for click to focus—that you’ve clicked where you intend to type. It’s very easy to get confused when moving between platforms using different input-focus methods.

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In X, the window manager or any other program can attach arbitrary commands to arbitrary user actions. For example, a program can attach the action of displaying a menu when a user right-clicks on the title bar. The window manager can pop-up a variety of menus when the user left-, right-, or center-clicks in the empty background of the windowing system; or it could happen when the user shift-left-, shift-right-, or shift-center-clicks—the possibilities are endless. One popular terminal program, xterm, pops up its configuration menus when the user holds down the control key and left-, right-, or center-clicks in the window. Some window managers attach a standard menu with common commands such as close and resize to each application’s title bar. Others attach these functions to pop-up menus or buttons in the title bar. You’ll find variations in program behavior even among different installations of the same UNIX flavor. Local configuration options can exert a significant influence over the interface. The best advice on how to find any particular option or command is to read the available documentation and to ask other local users.

Most window managers can iconize windows. Because the actual display of the client program’s windows isn’t handled by the client, the X server and window manager are free to make some useful contributions to the user experience. One of these contributions is that when the client requests a window with particular characteristics, the server isn’t obliged to represent the window that way to the user—it is required only to treat it as though it had those characteristics. This enables the server to, for example, scale the window arbitrarily, or to shrink it down and treat it as an icon. If you’re familiar with the idea of a task bar or application dock, you can think of iconized windows as windows that have been minimized, but that you can store anywhere on your screen.