bug#50067: Context menus

[Juri Linkov]

>> >> I guess the presence of the title should be platform-dependent.
>> >> For example, without a title it looks great on the GTK build.
>> >
>> > What happens if the GTK build displays a TTY frame?  Isn't the menu
>> > definition global, and thus doesn't distinguish between frame types?
>> 
>> The menu definition is constructed dynamically, so it possible
>> to set the title when (framep (selected-frame)) returns t on tty.
>
> OK, but as I wrote elsewhere, I think the string should always be
> present, and if some GUI toolkit wants to ignore it, it should avoid
> putting it into the native menu structure when it creates the menu
> widget(s).  The Lisp data should remain the same, IMO.

GUI toolkits can't ignore titles for all menus.  Some menus should be
displayed with a title for all toolkits.  The context menu is special.
Nowadays everyone is accustomed to down-mouse-3 popping up a context menu
without title.  But other Emacs-specific menus that are not familiar to users
such as mouse-buffer-menu bound C-<down-mouse-1> should display a title
for all toolkits to explain to the user what choice the menu presents.