even when emacsclient is started in a terminal, window-system is non-nil

Question

I want to call some functions when I run emacsclient in a terminal emulator. The code I have works when Emacs is started in a text-only terminal. When I start Emacs in graphical mode and run emacsclient -t in a terminal, the functions do not run so I cannot use the mouse in the terminal emulator.

Here is the code in question:

(defun my-terminal-config (&optional frame)
  "Establish settings for the current terminal."
  (message (format "%s" window-system)) ;; "ns" (Mac OS X) when Emacs is started graphically
  (message (format "%s" (display-graphic-p))) ;; nil when Emacs is started graphically
  (unless (display-graphic-p)
    ;; enable mouse reporting for terminal emulators
    (xterm-mouse-mode 1)
    (global-set-key [mouse-4] '(lambda ()
                                 (interactive)
                                 (scroll-down 1)))
    (global-set-key [mouse-5] '(lambda ()
                                 (interactive)
                                 (scroll-up 1)))))
(add-hook 'after-make-frame-functions 'my-terminal-config)

This is a weird situation. Emacsclient connects to the server and creates a new frame, but because the server is running in a graphical environment, it reports window-system to be "ns" whereas in a terminal environment it would be nil. Therefore when I run emacsclient -t in a terminal, the mouse reporting enabling functions do not run. Once emacsclient is running, if I create a new frame with C-x 5 2, then the mouse reporting enabling functions will run because window-system will be nil in that frame.

It seems that when mixing frames between terminals and window systems, the value of window-system will always be that of the Emacs server.

Is there a way that I can run Emacs graphically and emacsclient in text mode and have the mouse functions run there? In other words, is it possible to detect that a frame being created will end up in a graphical or text environment?

Maybe I should simply always run those functions when a frame is created regardless of the value of window-system?

Answer 1

the trick is that window-system and display-graphic-p are now frame specific. you need to be in that frame inside your hook function (seems like it should already be the case, but i don't think it is). i had to add this at the beginning of my after-make-frame-functions hook (to make window-system and display-graphic-p behave correctly):

(select-frame frame)