martin rudalics <rudalics@gmx.at> writes:

>> ConfigureNotify, PS=672x756, XS=1594x851, DS=672x756
>
> And this was a ConfigureNotify for the frame size the WM allots to us.
> This time it gives you the entire display - 1594x851 native pixels,
> right?.

The width seems right.  Not sure how much space my WM bar on top and
emacs' menubar have but I guess 851 pixel height is reasonable.

>>> Is this behavior new or did it already occur in Emacs 27?
>>
>> Yes, with my repro.el containing the `default-frame-alist' setting,
>> the initial frame has a menubar (until resize/focus), and the new
>> frame after C-x 5 2 has a scrollbar.
>
> And with Emacs 27 the initial frame did not have a menu bar initially
> and the new frame after C-x 5 2 did not have a scroll bar initially.
> Right?

No, what I've written above as answer to your question was with emacs
27.2.

> Did my latest commit (c18403302df3f07a7f94c3984d65b808fb40e8c1) in this
> area change anything in this regard?

Nope, "emacs -Q --load repro.el" (including `default-frame-alist'
setting) still results in

  1. initial frame has a menubar (fsh1.txt)
  2. C-x 5 2 frame has a scrollbar (fsh2.txt)

When commenting the `default-frame-alist' setting, all works as expected
(fsh3.txt for the initial frame and fsh4.txt for the new one created by
C-x 5 2).

When comparing fsh1 vs. fsh3, and fsh2 vs. fsh4, one can see that the
set_window_configuration calls are only there if `default-frame-alist'
is set.

Bye,
Tassilo