bug#46827: Broken initial size of GTK3 frame

[Juri Linkov]

> Let's check whether the frame code is affected.  With you original
> scenario and also with the two scenarios where you successfully suppress
> the flashes do

Actually, now there is only one successful scenario: it doesn't flash
with sit-for, but still flashes with a message.

> 1: Eval (setq frame-size-history '(100))
>
> 2: Run the Gnus setup
>
> 3: Eval (progn (frame--size-history) (pop-to-buffer "*frame-size-history*"))
>
> all in one and the same frame.  Then post the contents of the buffer
> *frame-size-history* for each of them.

1. when the frame flashes:

Frame size history of #<frame  *Minibuf-1* 0x55555935ffb0>
tab-bar-lines (3), TS=640x610~>640x612, TC=80x35~>80x36, IS=656x610~>656x612, 
MS=32x51 IH IV
tab-bar-lines (3), TS=640x612~>640x610, TC=80x36~>80x35, IS=656x612~>656x610, 
MS=80x85 IH IV
x_make_frame_visible
set_window_configuration (4), MS=80x85 IH IV

2. when no flash after adding sit-for in window--display-buffer:

Frame size history of #<frame  *Minibuf-1* 0x55555935ffb0>
tab-bar-lines (3), TS=640x610~>640x612, TC=80x35~>80x36, IS=656x610~>656x612, 
MS=32x51 IH IV
tab-bar-lines (3), TS=640x612~>640x610, TC=80x36~>80x35, IS=656x612~>656x610, 
MS=32x51 IH IV
x_make_frame_visible
set_window_configuration (4), MS=80x85 IH IV