Working with Windows
Until the introduction of the X Window System, many people happily used Emacs as their sole windowing system. Now Emacs and X have been integrated ( see Chapter 14 for more information on running Emacs under X), but in spite of this many people still use Emacs windowing capabilities, even under X. The truth is that Emacs windows do different things and boost your productivity in a different way than X does. As a result, you’ll want to know about Emacs windows regardless of whether you use X.
Earlier, we said that windows are areas on the screen in which Emacs displays the buffers that you are editing. You can have many windows on the screen at one time, each displaying a different buffer. Granted, the more windows you have, the smaller each one is; unlike X windows, Emacs windows can’t overlap, so as you add more windows, the older ones shrink. The screen is like a pie; you can cut it into many pieces, but the more pieces you cut, the smaller they are. You can place windows side-by-side, one on top of the other, or mix them. Each window has its own mode line that identifies the buffer name, the modes you’re running, and your position in the buffer. To make it clear where one window begins and another ends, mode lines are usually in reverse video.
As we’ve said, windows are not buffers. In fact, you can have more than one window on the same buffer. Doing so is often helpful if you want to look at different parts of a large file simultaneously. You can even have ...