Re: Mac: Don't quit Emacs when window is closed

[Nick Helm <nick@tenpoint.co.nz>]

> I have the problem that I always quit Emacs by mistake when I am done
> with a task by clicking the button to close the Emacs window. I have a
> few ideas / questions:
>
> - Wouldn't it be a good idea to make Emacs act like most Mac
> application and not quit the application when the window is closed? Is
> there some reason why this is not possible?
> - How can I disable the button to close the window or make it call
> suspend-frame instead of save-buffers-kill-emacs?

I wanted to do something similar on my mac-port emacs a while back and
added this to my init.el:

   (defun nick-mac-hide-last-frame (orig-fun &rest args)
      "Check if last visible frame is being closed and hide it instead."
      (if (and (featurep 'mac)
               (display-graphic-p nil)
               (= 1 (length (frame-list)))) (progn 
         (when (eq (frame-parameter (selected-frame) 'fullscreen) 'fullscreen)
            (set-frame-parameter (selected-frame) 'fullscreen nil) 
            (sit-for 1.2))
         (mac-do-applescript "tell application \"System Events\" \
            to tell process \"Emacs\" to set visible to false")
         (sit-for 1.5)
         (modify-frame-parameters (selected-frame) default-frame-alist)
         (delete-other-windows)
         (switch-to-buffer "*scratch*"))
        (apply orig-fun args)))

   (defun nick-handle-delete-frame (event)
      "Hide last visible frame when clicking frame close button."
      (interactive "e")
      (let ((frame (posn-window (event-start event))))
         (delete-frame frame t)))

   (defun nick-save-buffers-kill-terminal (&optional arg)
      "Hide last visible frame instead of closing Emacs."
      (interactive "P")
      (delete-frame (selected-frame) t))

   (advice-add 'delete-frame :around #'nick-mac-hide-last-frame)
   (advice-add 'handle-delete-frame :override #'nick-handle-delete-frame)
   (advice-add 'save-buffers-kill-terminal :override 
      #'nick-save-buffers-kill-terminal)

This uses applescript to hide the last frame instead of closing it. The
OS takes care of the unhiding when you click on the dock icon, relaunch
the app, double click a file, etc. Do Emacs > Quit Emacs or `kill-emacs'
to exit.

It doesn't leave the emacs menubar visible after a frame is closed, but
I've not found that to be a problem in practice. 

If you don't use the mac-port you can probably do the same thing by
dropping in ns-do-applescript, although I haven't tried it. 

Nick