Make the save buffers prompt from Quit Emacs menu more understandable

* lisp/files.el (save-buffers-kill-emacs): Use a much simpler (and
more understandable) prompt when exiting Emacs from the menu bar
(bug#4980).

* lisp/subr.el (use-dialog-box-p): Separate out into its own
function for reuse...
(y-or-n-p): ... from here.

2 files changed, 17 insertions, 5 deletions

diff --git a/lisp/files.el b/lisp/files.el
index 79c336f7825..9e8afc8d527 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -7752,7 +7752,15 @@ if any returns nil.  If `confirm-kill-emacs' is non-nil, calls it."
   (interactive "P")
   ;; Don't use save-some-buffers-default-predicate, because we want
   ;; to ask about all the buffers before killing Emacs.
-  (save-some-buffers arg t)
+  (if (use-dialog-box-p)
+      (pcase (x-popup-dialog
+              t `("Unsaved Buffers"
+                  ("Close Without Saving" . no-save)
+                  ("Save All" . save-all)
+                  ("Cancel" . cancel)))
+        ('cancel (user-error "Exit cancelled"))
+        ('save-all (save-some-buffers t)))
+    (save-some-buffers arg t))
   (let ((confirm confirm-kill-emacs))
     (and
      (or (not (memq t (mapcar (lambda (buf)
diff --git a/lisp/subr.el b/lisp/subr.el
index 29b9b6dfcf5..4b4412a883e 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -3249,6 +3249,13 @@ switch back again to the minibuffer before entering the
 character.  This is not possible when using `read-key', but using
 `read-key' may be less confusing to some users.")
 
+(defun use-dialog-box-p ()
+  "Say whether the user should be prompted with a dialog popup box."
+  (and (display-popup-menus-p)
+       last-input-event                 ; not during startup
+       (listp last-nonmenu-event)
+       use-dialog-box))
+
 (defun y-or-n-p (prompt)
   "Ask user a \"y or n\" question.
 Return t if answer is \"y\" and nil if it is \"n\".
@@ -3308,10 +3315,7 @@ like) while `y-or-n-p' is running)."
                   ((and (member str '("h" "H")) help-form) (print help-form))
                   (t (setq temp-prompt (concat "Please answer y or n.  "
                                                prompt))))))))
-     ((and (display-popup-menus-p)
-           last-input-event             ; not during startup
-           (listp last-nonmenu-event)
-           use-dialog-box)
+     ((use-dialog-box-p)
       (setq prompt (funcall padded prompt t)
             answer (x-popup-dialog t `(,prompt ("Yes" . act) ("No" . skip)))))
      (y-or-n-p-use-read-key