bug#66141: 29.1; Window size properties not set immediately for window in new frame

[Eli Zaretskii]

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> Date: Thu, 21 Sep 2023 20:48:19 +0200
> From: Mattias Nyrell <mattias@nyrell.se>
> 
> 
> 
> On 2023-09-21 18:39, Eli Zaretskii wrote:
> >> Date: Thu, 21 Sep 2023 18:16:01 +0200
> >> From: Mattias Nyrell <mattias@nyrell.se>
> >>
> >> Starting from emacs -Q, enter the following in *scratch*:
> >>
> >> (let ((f (make-frame '((fullscreen . maximized)))))
> >>     (select-frame-set-input-focus f)
> >>     (message "window-body-width=%s" (window-body-width))
> >>     (sleep-for 1)
> >>     (message "window-body-width=%s" (window-body-width)) )
> >>
> >> Execute with C-x C-e
> >>
> >> Result:
> >> - A new frame is created.
> >> - The message "window-body-width=80" is printed
> >> - The message "window-body-width=190" is printed (exact value depending
> >> on screen size of course)
> >>
> >> Expected result:
> >> The first printed message should be the same as the second printed message.
> > Isn't it because the actual resizing of the frame is done by the
> > window-system, and we can only ask it to do so?
> >
> > IOW, I think your expectation is incorrect, as it assumes that frame
> > move/resize operations are executed immediately.
> I have no idea, but your explanation sounds very reasonable and it is 
> probably right!
> 
> Is there a way to get notified when the resize operation has finished? 
> Or is sleeping for a short while a reasonable solution?

Yes, calling sleep-for is one way.  I would also suggest to try

  (sit-for 0)

If that works, it is faster.