bug#9923: 24.0.91; `where-is' does not find recentf menu items (cmds, not files)

[Juri Linkov]

> I'm wondering whether where-is could go at this the opposite direction.
> I mean, the menu system knows how to expand all this stuff...  so...
> could we ask it to do that, and then look at the results of that instead
> of parsing the keymap ourselves in where-is?

Another question: is it possible not to evaluate :filter in where-is as all?

Yesterday I added to context-menu-map such lines:

    (let ((fun (mouse-posn-property (event-start last-input-event)
                                    'context-menu-function)))

but now noticed that after typing 'C-h m' it fails with:

Debugger entered--Lisp error: (args-out-of-range 1786)
  mouse-posn-property((#<window 178 on *scratch*> 1786 (0 . 0) 0) 
context-menu-function)
  context-menu-map()
  (lambda (_) (context-menu-map))(ignore)
  where-is-internal(ignore nil t)
  #f(compiled-function (sym) #<bytecode -0x1145d1e4eb4c2a6>)(ignore)
  help-fns--list-local-commands()
  describe-mode()
  funcall-interactively(describe-mode)
  command-execute(describe-mode)

because context-menu functions are called from where-is-internal
without a mouse click.

Some time ago I already tried to workaround this problem
in help-mode-context-menu with:

  (when (and
         ;; First check if `help-fns--list-local-commands'
         ;; used `where-is-internal' to call this function
         ;; with wrong `last-input-event'.
         (eq (current-buffer) (window-buffer (posn-window (event-start 
last-input-event))))
         (mouse-posn-property (event-start last-input-event) 'mouse-face))

And now it reared its ugly head again.