bug#24803: Redirection problem with separate minibuffer frame

[martin rudalics <rudalics@gmx.at>]

 > I'm seeing redirection problems in my Emacs setup (with separate
 > minibuffer-only frame).  I suspect it comes from
 >
 >      commit 421c0512f76683e0b85ea5e1362291c2da4149ba
 >      Author: Martin Rudalics <rudalics@gmx.at>
 >      Date:   Mon Oct 17 10:52:01 2016 +0200
 >
 >        Fix frame focus redirection with shared minibuffer windows (Bug#24500)
 >
 >        * src/frame.c (do_switch_frame): Redirect frame focus also when
 >        the frame switched to has its minibuffer window on the selected
 >        frame.
 >        * src/window.c (candidate_window_p): To qualify as candidate
 >        it's not sufficient for the window's frame to just share the
 >        minibuffer window - it must be active as well.

Please revert the frame.c change so we can be sure which of the two is
the real culprit.

 > I just managed to reliably reproduce one of the symptoms of the problem:
 >
 >      % emacs -Q --eval "(setq default-frame-alist '((minibuffer)))"
 >      ... place the minibuffer frame so that half of it covers the main frame ...
 >      ... now from the minibuffer frame, do
 >      C-h f car RET
 >
 > at this point, the stacking order has been changed: the main frame is above
 > the minibuffer-only frame.  Then I move the mouse into the part of the
 > minibuffer frame still visible and I type
 >
 >      ffff
 >
 > The first `f` should call `find-file` (according to
 > minibuffer-inactive-mode-map), but instead the `ffff` text gets inserted
 > into the *scratch* buffer because of some inappropriate focus redirection.
 > [ This recipe depends on using a window-manager with
 >    focus-follows-mouse and it might also depend on other aspects of the
 >    window manager's behavior.  ]

Works as intended on both Windows XP and a GTK+ build with XFCE on
Debian.  I use focus-follows-mouse plus auto-raise-frame though the
minibuffer does _not_ get autoraised when moving the mouse there.
Actually, that's what I would call a misbehavior here ;-)

 > +      if (!NILP (FRAME_FOCUS_FRAME (XFRAME (frame)))
 > +          && !EQ (FRAME_FOCUS_FRAME (XFRAME (frame)), frame))
[...]
 > +  if (minibuf_level == 0)

Hmm... This seems to indicate that I do not remove the redirection when
exiting the minibuffer.  Could you try to augment in read_minibuf_unwind

   if (minibuf_level == 0)
     resize_mini_window (XWINDOW (window), 0);

to something that for each frame redirects focus to itself?  Obviously,
this might fail with recursive minibuffer invocations from two different
frames ...

martin