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Multiple Windows

Emacs can split the screen into two or many windows, which can display parts of different buffers, or different parts of one buffer.

Concepts of Emacs Windows

When multiple windows are being displayed, each window has an Emacs buffer designated for display in it. The same buffer may appear in more than one window; if it does, any changes in its text are displayed in all the windows where it appears. But the windows showing the same buffer can show different parts of it, because each window has its own value of point.

At any time, one of the windows is the selected window; the buffer this window is displaying is the current buffer. The terminal's cursor shows the location of point in this window. Each other window has a location of point as well, but since the terminal has only one cursor there is no way to show where those locations are.

Commands to move point affect the value of point for the selected Emacs window only. They do not change the value of point in any other Emacs window, even one showing the same buffer. The same is true for commands such as C-x b to change the selected buffer in the selected window; they do not affect other windows at all. However, there are other commands such as C-x 4 b that select a different window and switch buffers in it. Also, all commands that display information in a window, including (for example) C-h f (describe-function) and C-x C-b (list-buffers), work by switching buffers in a nonselected window without affecting the selected window.

Each window has its own mode line, which displays the buffer name, modification status and major and minor modes of the buffer that is displayed in the window. See section The Mode Line, for full details on the mode line.

Splitting Windows

C-x 2
Split the selected window into two windows, one above the other (split-window-vertically).
C-x 5
Split the selected window into two windows positioned side by side (split-window-horizontally).

The command C-x 2 (split-window-vertically) breaks the selected window into two windows, one above the other. Both windows start out displaying the same buffer, with the same value of point. By default the two windows each get half the height of the window that was split; a numeric argument specifies how many lines to give to the top window.

C-x 5 (split-window-horizontally) breaks the selected window into two side-by-side windows. A numeric argument specifies how many columns to give the one on the left. A line of vertical bars separates the two windows. Windows that are not the full width of the screen have mode lines, but they are truncated; also, they do not always appear in inverse video, because, the Emacs display routines have not been taught how to display a region of inverse video that is only part of a line on the screen.

When a window is less than the full width, text lines too long to fit are frequent. Continuing all those lines might be confusing. The variable truncate-partial-width-windows can be set non-nil to force truncation in all windows less than the full width of the screen, independent of the buffer being displayed and its value for truncate-lines. See section Continuation Lines.

Horizontal scrolling is often used in side-by-side windows. See section Controlling the Display.

Using Other Windows

C-x o
Select another window (other-window). That is o, not zero.
C-M-v
Scroll the next window (scroll-other-window).
M-x compare-windows
Find next place where the text in the selected window does not match the text in the next window.

To select a different window, use C-x o (other-window). That is an o, for `other', not a zero. When there are more than two windows, this command moves through all the windows in a cyclic order, generally top to bottom and left to right. From the rightmost and bottommost window, it goes back to the one at the upper left corner. A numeric argument means to move several steps in the cyclic order of windows. A negative argument moves around the cycle in the opposite order. When the minibuffer is active, the minibuffer is the last window in the cycle; you can switch from the minibuffer window to one of the other windows, and later switch back and finish supplying the minibuffer argument that is requested. See section Editing in the Minibuffer.

The usual scrolling commands (see section Controlling the Display) apply to the selected window only, but there is one command to scroll the next window. C-M-v (scroll-other-window) scrolls the window that C-x o would select. It takes arguments, positive and negative, like C-v.

The command M-x compare-windows compares the text in the current window with that in the next window. Comparison starts at point in each window. Point moves forward in each window, a character at a time in each window, until the next characters in the two windows are different. Then the command is finished.

Displaying in Another Window

C-x 4 is a prefix key for commands that select another window (splitting the window if there is only one) and select a buffer in that window. Different C-x 4 commands have different ways of finding the buffer to select.

C-x 4 b bufname RET
Select buffer bufname in another window. This runs switch-to-buffer-other-window.
C-x 4 f filename RET
Visit file filename and select its buffer in another window. This runs find-file-other-window. See section Visiting Files.
C-x 4 d directory RET
Select a Dired buffer for directory directory in another window. This runs dired-other-window. See section Dired, the Directory Editor.
C-x 4 m
Start composing a mail message in another window. This runs mail-other-window, and its same-window version is C-x m (see section Sending Mail).
C-x 4 .
Find a tag in the current tag table in another window. This runs find-tag-other-window, the multiple-window variant of M-. (see section Tag Tables).

Deleting and Rearranging Windows

C-x 0
Get rid of the selected window (kill-window). That is a zero.
C-x 1
Get rid of all windows except the selected one (delete-other-windows).
C-x ^
Make the selected window taller, at the expense of the other(s) (enlarge-window).
C-x }
Widen the selected window (enlarge-window-horizontally).

To delete a window, type C-x 0 (delete-window). (That is a zero.) The space occupied by the deleted window is distributed among the other active windows (but not the minibuffer window, even if that is active at the time). Once a window is deleted, its attributes are forgotten; there is no automatic way to make another window of the same shape or showing the same buffer. But the buffer continues to exist, and you can select it in any window with C-x b.

C-x 1 (delete-other-windows) is more powerful than C-x 0; it deletes all the windows except the selected one (and the minibuffer); the selected window expands to use the whole screen except for the echo area.

To readjust the division of space among existing windows, use C-x ^ (enlarge-window). It makes the currently selected window get one line bigger, or as many lines as is specified with a numeric argument. With a negative argument, it makes the selected window smaller. C-x } (enlarge-window-horizontally) makes the selected window wider by the specified number of columns. The extra screen space given to a window comes from one of its neighbors, if that is possible; otherwise, all the competing windows are shrunk in the same proportion. If this makes any windows too small, those windows are deleted and their space is divided up. The minimum size is specified by the variables window-min-height and window-min-width.

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