Emacs/docs/latest/emacs/Pop-Up-Window

20.4 Displaying in Another Window

C-x 4 is a prefix key for a variety of commands that switch to a buffer in a different window—either another existing window, or a new window created by splitting the selected window. See Window Choice, for how Emacs picks or creates the window to use.

C-x 4 b bufname RET

Select buffer bufname in another window (switch-to-buffer-other-window). See Select Buffer.

C-x 4 C-o bufname RET

Display buffer bufname in some window, without trying to select it (display-buffer). See Displaying Buffers, for details about how the window is chosen.

C-x 4 f filename RET

Visit file filename and select its buffer in another window (find-file-other-window). See Visiting.

C-x 4 d directory RET

Select a Dired buffer for directory directory in another window (dired-other-window). See Dired.

C-x 4 m

Start composing a mail message, similar to C-x m (see Sending Mail), but in another window (compose-mail-other-window).

C-x 4 .

Find the definition of an identifier, similar to M-. (see Xref), but in another window (xref-find-definitions-other-window).

C-x 4 r filename RET

Visit file filename read-only, and select its buffer in another window (find-file-read-only-other-window). See Visiting.