bug#11732: Follow-up to bug#11732

[Eli Zaretskii]

> Date: Tue, 03 Jul 2018 10:29:59 +0200
> From: martin rudalics <rudalics@gmx.at>
> CC: mhatta@gmail.com, 11732@debbugs.gnu.org
> 
> No further explanations needed, the problem is clearly visible here
> now.  Do you have any explanation why calling DefWindowProc when
> handling WM_IME_STARTCOMPOSITION causes this aberrant behavior and not
> any of the other cases where we call DefWindowProc?

None whatsoever.

Moreover, I sometimes see the same problem in my "normal" Emacs
session running 26.1 sources where this change was not done (but in
"emacs -Q" I cannot trigger the problem unless I make the change).

So I think it's not the proposed change that does it, it's something
we don't do entirely correctly that interacts badly with
focus-follows-mouse configuration.  Which is why I said that unless
you have ideas how to fix this, we should simply install the proposed
change, and deal with the dialog problems separately, perhaps using
the changes I tried and you fixed.