bug#61667: 29.0.60; Failure to redisplay

[Dmitry Gutov]

On 16/04/2023 15:59, Eli Zaretskii wrote:
> > Date: Sun, 16 Apr 2023 15:52:51 +0300
> > Cc:luangruo@yahoo.com,61667@debbugs.gnu.org,gregory@heytings.org
> > From: Dmitry Gutov<dgutov@yandex.ru>
> >
> > On 16/04/2023 09:01, Eli Zaretskii wrote:
> > > > Date: Sun, 16 Apr 2023 03:48:56 +0300
> > > > From: Dmitry Gutov<dgutov@yandex.ru>
> > > > Cc: Gregory Heytings<gregory@heytings.org>, Eli Zaretskii<eliz@gnu.org>,
> > > >    Po Lu<luangruo@yahoo.com>
> > > >
> > > > - Do some search using 'C-x p g', wait to see the results buffer
> > > > displayed but it's not displayed for a while. I look at the title bar -
> > > > and it already says*xref*, but the frame is still not updated. If I
> > > > press something like 'C-n' or 'C-f' now, that triggers the necessary
> > > > refresh.
> > > >
> > > > - When the said Xref buffers is selected, I press 'q'. Likewise, the
> > > > frame might not get updated for a while, still showing the previous
> > > > window configuration until I issue the next command.
> > > >
> > > > These are of course random and don't happen every time. Often enough to
> > > > be annoying, though.
> > > Is this with or without double-buffering?  If it's with
> > > double-buffering, do the problems go away if you disable
> > > double-buffering?
> > Good question: the above failure scenario reproduces even without XDBE.
> > The frequency is about the same as with XDBE.
> Thanks.  Next question: does it reproduce easily in "emacs -Q"?

It does. As soon as I disable scroll-bar-mode, menu-bar-mode, 
tool-bar-mode and blink-cursor-mode.

It goes like this:

1. 'emacs -Q', disable stuff.
2. 'C-x p f', visit lisp/emacs-lisp/smie.el.
3. Search for something rare using 'C-x p g' (e.g. for "Coq-specific", 
but not necessarily).
4. Press 'q' to exit the search.

On step 3 or 4, the title bar will get updated noticeably faster than 
the frame configuration changes.