bug#49466: 28.0.50; C-<mouse-2> is undefined

[Juri Linkov]

The Info manual says in (info "(emacs) Menu Mouse Clicks")

  ‘C-mouse-2’
       This menu contains entries for examining faces and other text
       properties, and well as for setting them (the latter is mainly
       useful when editing enriched text; *note Enriched Text::).

But clicking C-mouse-2 signals the error:

  C-<mouse-2> is undefined

The above Info node has a link to the "Enriched Text" node
where (info "(emacs) Editing Format Info") says:

  The easiest way to alter properties is with the ‘Text Properties’ menu.
  You can get to this menu from the ‘Edit’ menu in the menu bar (*note
  Menu Bar::), or with ‘C-mouse-2’ (*note Menu Mouse Clicks::).

However, ‘C-mouse-2’ fails even in enriched-mode,
e.g. after visiting etc/enriched.txt.

Also the documented ‘Text Properties’ menu
is not displayed in enriched-mode.

PS: There is also this comment in lisp/mouse.el,
maybe it should be removed:

  ;; C-down-mouse-2 is bound in facemenu.el.