Replace flyspell-use-mouse-3-for-menu with context-menu-mode (bug#50067)

* doc/emacs/fixit.texi (Spelling): Replace mentions of
flyspell-use-mouse-3-for-menu with context-menu-mode.

* lisp/mouse.el (context-menu-map): Use the function from the
text property context-menu-function at mouse click event.

* lisp/textmodes/flyspell.el (flyspell--set-use-mouse-3-for-menu):
Remove function.
(flyspell-use-mouse-3-for-menu): Remove defcustom added recently in 28.1.
(flyspell-context-menu): New function.
(flyspell-mode): Don't call flyspell--set-use-mouse-3-for-menu.
(flyspell-mode-on): Replace flyspell-use-mouse-3-for-menu
with context-menu-mode.
(make-flyspell-overlay): When context-menu-mode is non-nil,
put overlay context-menu-function with flyspell-context-menu
instead of using keymap flyspell-mouse-map.

doc/emacs/fixit.texi

@@ -462,10 +462,9 @@ use @code{flyspell-region} or @code{flyspell-buffer} for that.
   When Flyspell mode highlights a word as misspelled, you can click on
 it with @kbd{mouse-2} (@code{flyspell-correct-word}) to display a menu
 of possible corrections and actions.  If you want this menu on
-@kbd{mouse-3} instead, customize the variable
-@code{flyspell-use-mouse-3-for-menu}.  In addition, @kbd{C-.} or
-@kbd{@key{ESC}-@key{TAB}} (@code{flyspell-auto-correct-word}) will
-propose various successive corrections for the word at point, and
+@kbd{mouse-3} instead, enable @code{context-menu-mode}.  In addition,
+@kbd{C-.} or @kbd{@key{ESC}-@key{TAB}} (@code{flyspell-auto-correct-word})
+will propose various successive corrections for the word at point, and
 @w{@kbd{C-c $}} (@code{flyspell-correct-word-before-point}) will pop
 up a menu of possible corrections.  Of course, you can always correct
 the misspelled word by editing it manually in any way you like.

etc/NEWS

@@ -2875,8 +2875,7 @@ like 'flymake-mode-line-error-counter',
 When Flyspell mode highlights a word as misspelled, you can click on
 it to display a menu of possible corrections and actions.  You can now
 easily bind this menu to 'down-mouse-3' (usually the right mouse button)
-instead of 'mouse-2' (the default) by customizing the new user option
-'flyspell-use-mouse-3-for-menu'.
+instead of 'mouse-2' (the default) by enabling 'context-menu-mode'.
 
 ---
 *** The current dictionary is now displayed in the minor mode lighter.

lisp/mouse.el

@@ -307,10 +307,15 @@ the same menu with changes such as added new menu items."
 (defun context-menu-map ()
   "Return composite menu map."
   (let ((menu (make-sparse-keymap (propertize "Context Menu" 'hide t))))
-    (run-hook-wrapped 'context-menu-functions
-                      (lambda (fun)
-                        (setq menu (funcall fun menu))
-                        nil))
+    (let ((fun (mouse-posn-property (event-start last-input-event)
+                                    'context-menu-function)))
+      (if (functionp fun)
+          (setq menu (funcall fun menu))
+        (run-hook-wrapped 'context-menu-functions
+                          (lambda (fun)
+                            (setq menu (funcall fun menu))
+                            nil))))
+    ;; TODO: remove double separators
     (when (functionp context-menu-filter-function)
       (setq menu (funcall context-menu-filter-function menu)))
     menu))

lisp/textmodes/flyspell.el

@@ -442,22 +442,6 @@ like <img alt=\"Some thing.\">."
     map)
   "Minor mode keymap for Flyspell mode--for the whole buffer.")
 
-;; correct on mouse 3
-(defun flyspell--set-use-mouse-3-for-menu (var value)
-  (set-default var value)
-  (if value
-      (progn (define-key flyspell-mouse-map [mouse-2] nil)
-             (define-key flyspell-mouse-map [down-mouse-3] 'flyspell-correct-word))
-    (define-key flyspell-mouse-map [mouse-2] 'flyspell-correct-word)
-    (define-key flyspell-mouse-map [down-mouse-3] nil)))
-
-(defcustom flyspell-use-mouse-3-for-menu nil
-  "Non-nil means to bind `mouse-3' to `flyspell-correct-word'.
-If this is set, also unbind `mouse-2'."
-  :type 'boolean
-  :set 'flyspell--set-use-mouse-3-for-menu
-  :version "28.1")
-
 ;; dash character machinery
 (defvar-local flyspell-consider-dash-as-word-delimiter-flag nil
   "Non-nil means that the `-' char is considered as a word delimiter.")
@@ -486,6 +470,13 @@ See also `flyspell-duplicate-distance'."
 
 (defvar flyspell-overlay nil)
 
+(defun flyspell-context-menu (_menu)
+  "Context menu for `context-menu-mode'."
+  ;; TODO: refactor `flyspell-correct-word' and related functions to return
+  ;; a keymap menu where every menu item is bound to a lambda that calls
+  ;; `flyspell-do-correct' with an argument that is a correct word.
+  'flyspell-correct-word)
+
 ;;*---------------------------------------------------------------------*/
 ;;*    flyspell-mode ...                                                */
 ;;*---------------------------------------------------------------------*/
@@ -537,10 +528,7 @@ in your init file.
   :group 'flyspell
   (if flyspell-mode
       (condition-case err
-          (progn
-            (when flyspell-use-mouse-3-for-menu
-              (flyspell--set-use-mouse-3-for-menu 'flyspell-use-mouse-3-for-menu t))
-            (flyspell-mode-on (called-interactively-p 'interactive)))
+	  (flyspell-mode-on (called-interactively-p 'interactive))
 	(error (message "Error enabling Flyspell mode:\n%s" (cdr err))
 	       (flyspell-mode -1)))
     (flyspell-mode-off)))
@@ -656,8 +644,7 @@ are both non-nil."
            show-msg)
       (let* ((binding (where-is-internal 'flyspell-auto-correct-word
                                          nil 'non-ascii))
-             (mouse-button (if flyspell-use-mouse-3-for-menu
-                               "Mouse-3" "Mouse-2")))
+             (mouse-button (if context-menu-mode "Mouse-3" "Mouse-2")))
         (message (format-message
                   "Welcome to Flyspell. Use %s to correct words."
                   (if binding
@@ -1820,13 +1807,15 @@ for the overlay."
     (overlay-put overlay 'mouse-face mouse-face)
     (overlay-put overlay 'flyspell-overlay t)
     (overlay-put overlay 'evaporate t)
-    (overlay-put overlay 'help-echo (concat (if flyspell-use-mouse-3-for-menu
-                                                "mouse-3"
-                                              "mouse-2") ": correct word at point"))
-    ;; If misspelled text has a 'keymap' property, let that remain in
-    ;; effect for the bindings that flyspell-mouse-map doesn't override.
-    (set-keymap-parent flyspell-mouse-map (get-char-property beg 'keymap))
-    (overlay-put overlay 'keymap flyspell-mouse-map)
+    (overlay-put overlay 'help-echo
+                 (concat (if context-menu-mode "mouse-3" "mouse-2")
+                         ": correct word at point"))
+    (if context-menu-mode
+        (overlay-put overlay 'context-menu-function 'flyspell-context-menu)
+      ;; If misspelled text has a 'keymap' property, let that remain in
+      ;; effect for the bindings that flyspell-mouse-map doesn't override.
+      (set-keymap-parent flyspell-mouse-map (get-char-property beg 'keymap))
+      (overlay-put overlay 'keymap flyspell-mouse-map))
     (when (eq face 'flyspell-incorrect)
       (and (stringp flyspell-before-incorrect-word-string)
            (overlay-put overlay 'before-string