bug#18722: Correction

[Eli Zaretskii]

> Date: Thu, 16 Oct 2014 10:52:23 +0200
> From: martin rudalics <rudalics@gmx.at>
> 
>  > Actions that trigger the bug:
>  >
>  > 1. Start emacs -Q.
>  > 2. Unfocus the application window, e.g., by clicking on another
>  > application.
>  > 3. Re-focus Emacs.
>  > 4. Write something.
>  >
>  > Result: The typed text does not appear.  When I click on a menu-item,
>  > the typed text appears and the UI is responsive again.
> 
>  > The problem seems to appear when I iconify and reopen the Emacs
>  > window.  Unfocusing the Emacs window alone is not enough to trigger the
>  > bug.  Also it seems that Emacs is responding to my input.  It just
>  > doesn't render changes in the windows and the minibuffer.
> 
> I see something similar when I minimize the maximized window of another
> application and (presumably, implicitly) re-focus the Emacs window.  But
> I have no good recipe to trigger it reliably.

I think we are relying on X expose events in these cases.  Maybe this
particular window manager doesn't send them?

I'm not sure I understand this part:

 > Also it seems that Emacs is responding to my input.  It just
 > doesn't render changes in the windows and the minibuffer.

If Emacs doesn't redisplay the changes, then what does "is responding
to changes" mean?  How do you even kn ow Emacs responds to changes, if
it doesn't redisplay?