bug#20677: tooltips generate garbage

[Eli Zaretskii]

> From: Michael Heerdegen <michael_heerdegen@web.de>
> Cc: 20677@debbugs.gnu.org,  angelo.graziosi@alice.it
> Date: Wed, 03 Jun 2015 18:10:00 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > > > Can you see whether Emacs gets an expose event when the tip pops
> > > > down?
> 
> > If your Emacs was configured with --enable-checking='yes,glyphs', then
> > you can see the fact that the function is called announced on stderr
> > after invoking "M-x trace-redisplay RET".  (If you do that, I suggest
> > to turn off blink-cursor-mode first, to reduce clutter from redisplay
> > cycles induced by the blinking.)
> 
> I tried just that.  Whenever the tip pops down, I get one expose_frame
> followed by one expose_window.

And the patches proposed by Yamamoto-san, do they fix the problem for
you as well?