bug#51173: 28.0.60; gnus-article-describe-key doesn't work

[Juri Linkov]

> But this will still use "the wrong buffer" for mouse clicks, no?
>
> BTW, maybe a cleaner fix would be as follows:
> - Add a `buffer` argument to `describe-key(-briefly)`.
> - Pass that argument from `gnus-article-describe-key`.
> And to get the behavior that Juri just pushed that `buffer` argument
> would default to (if (consp event) (window-buffer (posn-window
> (event-start event))) (current-buffere)).

Maybe something like this (but currently I have no idea how to test all cases):

diff --git a/lisp/help.el b/lisp/help.el
index 9666ef9805..08a293c3dc 100644
--- a/lisp/help.el
+++ b/lisp/help.el
@@ -731,7 +731,7 @@ help--filter-info-list
    ;; If nothing left, then keep one (the last one).
    (last info-list)))
 
-(defun describe-key-briefly (&optional key-list insert untranslated)
+(defun describe-key-briefly (&optional key-list insert buffer)
   "Print the name of the functions KEY-LIST invokes.
 KEY-LIST is a list of pairs (SEQ . RAW-SEQ) of key sequences, where
 RAW-SEQ is the untranslated form of the key sequence SEQ.
@@ -739,8 +739,10 @@ describe-key-briefly
 
 While reading KEY-LIST interactively, this command temporarily enables
 menu items or tool-bar buttons that are disabled to allow getting help
-on them."
-  (declare (advertised-calling-convention (key-list &optional insert) "27.1"))
+on them.
+
+BUFFER is the buffer in which to lookup those keys; it defaults to the
+current buffer."
   (interactive
    ;; Ignore mouse movement events because it's too easy to miss the
    ;; message while moving the mouse.
@@ -748,15 +750,13 @@ describe-key-briefly
      `(,key-list ,current-prefix-arg)))
   (when (arrayp key-list)
     ;; Old calling convention, changed
-    (setq key-list (list (cons key-list
-                               (if (numberp untranslated)
-                                   (this-single-command-raw-keys)
-                                 untranslated)))))
-  (let* ((info-list (mapcar (lambda (kr)
-                              (help--analyze-key (car kr) (cdr kr)))
-                            key-list))
-         (msg (mapconcat #'car (help--filter-info-list info-list 1) "\n")))
-    (if insert (insert msg) (message "%s" msg))))
+    (setq key-list (list (cons key-list nil))))
+  (with-current-buffer (or buffer (current-buffer))
+    (let* ((info-list (mapcar (lambda (kr)
+                                (help--analyze-key (car kr) (cdr kr)))
+                              key-list))
+           (msg (mapconcat #'car (help--filter-info-list info-list 1) "\n")))
+      (if insert (insert msg) (message "%s" msg)))))
 
 (defun help--key-binding-keymap (key &optional accept-default no-remap 
position)
   "Return a keymap holding a binding for KEY within current keymaps.
diff --git a/lisp/gnus/gnus-art.el b/lisp/gnus/gnus-art.el
index bb466b9400..bbb452279a 100644
--- a/lisp/gnus/gnus-art.el
+++ b/lisp/gnus/gnus-art.el
@@ -6865,8 +6865,14 @@ gnus-article-describe-key
               unread-command-events))
        (let ((cursor-in-echo-area t)
              gnus-pick-mode)
-         (describe-key (read-key-sequence nil t))))
-    (describe-key key)))
+         (let* ((key (read-key-sequence nil t))
+                 (buffer (if (consp key)
+                             (window-buffer (posn-window (event-start key)))
+                           (current-buffer))))
+            (describe-key key buffer))))
+    (describe-key key (if (consp key)
+                          (window-buffer (posn-window (event-start key)))
+                        (current-buffer)))))
 
 (defun gnus-article-describe-key-briefly (key &optional insert)
   "Display documentation of the function invoked by KEY.
@@ -6888,8 +6894,15 @@ gnus-article-describe-key-briefly
               unread-command-events))
        (let ((cursor-in-echo-area t)
              gnus-pick-mode)
-         (describe-key-briefly (read-key-sequence nil t) insert)))
-    (describe-key-briefly key insert)))
+         (let ((key (read-key-sequence nil t))
+                (buffer (if (consp key)
+                            (window-buffer (posn-window (event-start key)))
+                          (current-buffer))))
+            (describe-key-briefly key insert buffer))))
+    (describe-key-briefly key insert
+                          (if (consp key)
+                              (window-buffer (posn-window (event-start key)))
+                            (current-buffer)))))
 
 ;;`gnus-agent-mode' in gnus-agent.el will define it.
 (defvar gnus-agent-summary-mode)