P.10 Multiple Displays

A single Emacs can talk to more than one X display. Initially, Emacs uses just one display--the one specified with the DISPLAY environment variable or with the `--display' option (see section AE.2 Initial Options). To connect to another display, use the command make-frame-on-display:

M-x make-frame-on-display RET display RET

Create a new frame on display display.

A single X server can handle more than one screen. When you open frames on two screens belonging to one server, Emacs knows they share a single keyboard, and it treats all the commands arriving from these screens as a single stream of input.

When you open frames on different X servers, Emacs makes a separate input stream for each server. This way, two users can type simultaneously on the two displays, and Emacs will not garble their input. Each server also has its own selected frame. The commands you enter with a particular X server apply to that server's selected frame.

Despite these features, people using the same Emacs job from different displays can still interfere with each other if they are not careful. For example, if any one types C-x C-c, that exits the Emacs job for all of them!