Subject: bug#61667: 29.0.60; Failure to redisplay

From: Dmitry Gutov <[email-masked]>
Date: Tue, 28 Feb 2023 19:59:24 +0200

On 28/02/2023 12:31, Po Lu wrote:
> Gregory Heytings <[email-masked]> writes:
> 
>> Thanks!  After seeing this, I'm now convinced that the problem is not
>> a GNOME one, for two reasons:
>>
>> 1.  The effect of (insert "!") (redisplay) is immediately visible on
>> screen.  Why would GNOME treat the effect of changing the buffer from
>> *scratch* to xassociations.rb differently?
> 
> If you insert "!", the frame title does not change, right?
"!" is inserted in the same buffer the command is invoked from - so the 
title shouldn't change at that point yet.

> Everything points to this being a bug somewhere in Mutter: how damage to
> surrounding windows (including obscured ones) prevents it from showing
> up, and how it doesn't show up in an undecorated frame.

Why does constant frame-title-format fix this, though?

> Dimitry, do you see any delay between the change in the frame title and
> when ``Test 2'' becomes visible?  With and without double buffering, and
> with and without `undecorated' set to `t'?
> 
>    (progn
>      (sleep-for 1)
>      (setq frame-title-format icon-title-format)
>      (insert "Test 1")
>      (force-mode-line-update)
>      (redisplay)
>      (sleep-for 1)
>      (setq frame-title-format "test title")
>      (insert "Test 2")
>      (force-mode-line-update)
>      (redisplay))

I have tried this with default config (double buffering on, undecorated 
off), and I don't see any delay between text insertion and frame title 
changes. 1 second pause, "Test 1" is inserted, the title changes (*), 1 
second pause, "Test 2" is inserted, the title changes.

That probably means I don't need to test the alternative configs, right?

(*) By default frame-title-format is eq to icon-title-format, so with 
'emacs -Q' the title doesn't actually change on the first step. I tried 
both this scenario and the scenario with swapped frame-title-format 
assignments. In both the second insertion of "Test 2" coincides with the 
title change to "test title".