Subject: Re: bug#61667: 29.0.60; Failure to redisplay

From: Dmitry Gutov <[email-masked]>
Date: Thu, 2 Mar 2023 14:29:46 +0200

On 02/03/2023 12:29, Po Lu wrote:
>> And the next one (the last one) happens much later. From further
>> testing, it seems to correlate to me typing 'C-x C-c', rather than to
>> when the frame finally refreshes after the delay (for example, when I
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> decide to stop waiting and hover with the mouse over the frame, or
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> over the title bar buttons).
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^
> Hovering over the title bar buttons generates damage on the window and
> causes Mutter to ``wake up'', prior to anything further buffer flipping
> by Emacs.  Mutter cannot magically pull undisplayed frame contents out
> of Emacs.

Is that much different from being affected by a background window? Which 
we knew from previous experiments.

A background window changing generates damage, causing Mutter to 
refresh... something.