bug#50067: Context menus

[Juri Linkov]

>> * flyspell menu
>>
>> It is handy to show 'flyspell-correct-word when click on typo word.
>> However, menu is embedded inside of pre existing
>> 'flyspell-correct-word and it is hard to collect menu.  Since
>> popup-menu interface can accept both menu and function with `e', it's
>> good to utilize 'flyspell-correct-word.
>>
>> How about something like below to interrupt evaluation of
>> context-menu-functions in the middle when one of
>> context-menu-functions returns symbol instead of menu?
>
> Thanks, adapting flyspell to use the context menu is our next priority.
> But it seems interrupting evaluation is too hackish solution, and it still
> uses x-popup-menu.  Would it be possible for flyspell to put its context
> function to the end of context-menu-functions, and then replace all
> previously added menus with own menu that contains word corrections?

Here is the first step that adds support for overlay-local context-menu,
and removes the recently added 'flyspell-use-mouse-3-for-menu'.
But 'flyspell-context-menu' still returns 'flyspell-correct-word'.

I invite you or anyone else to refactor 'flyspell-correct-word' and
related functions to return a keymap menu where every menu item
is bound to a function that calls flyspell-do-correct with an argument
that is a correct word.

diff --git a/doc/emacs/fixit.texi b/doc/emacs/fixit.texi
index b558ebc3fd..85cdbff5fa 100644
--- a/doc/emacs/fixit.texi
+++ b/doc/emacs/fixit.texi
@@ -462,10 +462,9 @@ Spelling
   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.
diff --git a/etc/NEWS b/etc/NEWS
index 04e482364a..a6d9b3a8b8 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2889,8 +2893,7 @@ 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.
diff --git a/lisp/mouse.el b/lisp/mouse.el
index d137419e02..f52fb3f6ba 100644
--- a/lisp/mouse.el
+++ b/lisp/mouse.el
@@ -307,10 +307,15 @@ context-menu-filter-function
 (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))
diff --git a/lisp/textmodes/flyspell.el b/lisp/textmodes/flyspell.el
index 836d889a1c..c05be9655f 100644
--- a/lisp/textmodes/flyspell.el
+++ b/lisp/textmodes/flyspell.el
@@ -442,22 +442,6 @@ flyspell-mode-map
     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 +470,10 @@ flyspell-duplicate
 
 (defvar flyspell-overlay nil)
 
+(defun flyspell-context-menu (_menu)
+  "Context menu for `context-menu-mode'."
+  'flyspell-correct-word)
+
 ;;*---------------------------------------------------------------------*/
 ;;*    flyspell-mode ...                                                */
 ;;*---------------------------------------------------------------------*/
@@ -537,10 +525,7 @@ flyspell-mode
   :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 +641,7 @@ flyspell-mode-on
            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 +1804,15 @@ make-flyspell-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