bug#52666: 27.0.50; Unexpected mode line flickering when creating frames

[Eli Zaretskii]

> Cc: Eli Zaretskii <eliz@gnu.org>, 52666@debbugs.gnu.org
> From: martin rudalics <rudalics@gmx.at>
> Date: Wed, 22 Dec 2021 10:22:57 +0100
> 
>  >      39.2 Forcing Redisplay
>  >      ======================
>  >
>  >      Emacs normally tries to redisplay the screen whenever it waits for
>  >      input.
>  >
>  > In the example that exhibits the flickering, there is no waiting for
>  > input between the creation of the frame and the change of its width and
>  > height.
> 
> Maybe that line is confusing.

Not really.  It says "normally", and that is accurate.  There are
other situations where Emacs does redisplay, either because some Lisp
program forced it to do so, or for other reasons.

The ELisp manual has limitations if treated as documentation of the
Emacs internals -- that's not its purpose.

> Emacs may have to redisplay whenever it
> receives a corresponding event (like Map, Visibility, Expose and Focus
> notifications).  Waiting for user input is only a tangential aspect
> there.

Not entirely, or at least not always: Emacs ("normally") reads events
when it waits for input.