GNU Info

(elisp)Multiple Displays

---

Next: Frame Parameters Prev: Creating Frames Up: Frames

---

Enter node , (file) or (file)node

Multiple Displays
=================

   A single Emacs can talk to more than one X display.  Initially,
Emacs uses just one display--the one chosen with the `DISPLAY'
environment variable or with the `--display' option (Note: Initial
Options.).  To connect to another display, use
the command `make-frame-on-display' or specify the `display' frame
parameter when you create the frame.

   Emacs treats each X server as a separate terminal, giving each one
its own selected frame and its own minibuffer windows.  However, only
one of those frames is "_the_ selected frame" at any given moment, see
Note: Input Focus.

   A few Lisp variables are "terminal-local"; that is, they have a
separate binding for each terminal.  The binding in effect at any time
is the one for the terminal that the currently selected frame belongs
to.  These variables include `default-minibuffer-frame',
`defining-kbd-macro', `last-kbd-macro', and `system-key-alist'.  They
are always terminal-local, and can never be buffer-local (Note:
Buffer-Local Variables) or frame-local.

   A single X server can handle more than one screen.  A display name
`HOST:SERVER.SCREEN' has three parts; the last part specifies the
screen number for a given server.  When you use two screens belonging
to one server, Emacs knows by the similarity in their names that they
share a single keyboard, and it treats them as a single terminal.

 - Command: make-frame-on-display display &optional parameters
     This creates a new frame on display DISPLAY, taking the other
     frame parameters from PARAMETERS.  Aside from the DISPLAY
     argument, it is like `make-frame' (Note: Creating Frames).

 - Function: x-display-list
     This returns a list that indicates which X displays Emacs has a
     connection to.  The elements of the list are strings, and each one
     is a display name.

 - Function: x-open-connection display &optional xrm-string must-succeed
     This function opens a connection to the X display DISPLAY.  It
     does not create a frame on that display, but it permits you to
     check that communication can be established with that display.

     The optional argument XRM-STRING, if not `nil', is a string of
     resource names and values, in the same format used in the
     `.Xresources' file.  The values you specify override the resource
     values recorded in the X server itself; they apply to all Emacs
     frames created on this display.  Here's an example of what this
     string might look like:

          "*BorderWidth: 3\n*InternalBorder: 2\n"

     Note: Resources.

     If MUST-SUCCEED is non-`nil', failure to open the connection
     terminates Emacs.  Otherwise, it is an ordinary Lisp error.

 - Function: x-close-connection display
     This function closes the connection to display DISPLAY.  Before
     you can do this, you must first delete all the frames that were
     open on that display (Note: Deleting Frames).