Re: menu-bar: disable items when no frame visible

[Juri Linkov <juri@jurta.org>]

>     GTK menus can be detached from their frame. I am not absolutely sure
>     (and not able to test right now) what happens if you minimize their
>     frame (or otherwise make it invisible) though.
>
> Can someone tell us what the detached GTK menu bar does
> when there is no visible frame?  Which frame does it operate on?

It operates on the frame from which it was detached.  This frame
remains invisible after selecting a menu item from the visible menu.

> Is the suggestion (or menu-updating-frame (selected-frame)) correct
> for the GTK case?

At least, it doesn't make things worse.  I discovered that currently
even GTK builds have the same bug as on non-toolkit builds.  For example,
after evaluating on a GTK build:

  (define-key global-map [down-mouse-3] menu-bar-file-menu)

the menu item "Save As..." is disabled in the popup menu called via [mouse-3].

After looking at the code I suspect that the same bug exists on W32 and OSX.
In w32menu.c and macmenu.c `x-popup-menu' after setting Vmenu_updating_frame
to the frame `f', resets it immediately to nil, so Vmenu_updating_frame
eventually is always nil in popup menus.  And xmenu.c doesn't set
Vmenu_updating_frame at all in `x-popup-menu'.  I guess the correct code
for all three platforms should be:

  if (! NILP (position))
    {
      ...

      XSETFRAME (Vmenu_updating_frame, f);
    }
  else
    Vmenu_updating_frame = Qnil;

Is it right?

-- 
Juri Linkov
http://www.jurta.org/emacs/