bug#46827: Broken initial size of GTK3 frame

[Juri Linkov]

>> It seems tab-bar.el already updates only between 0 and 1.
>
> That's not what I've seen.

There are no other values used in source code of tab-bar.el.
But maybe sometimes the value of tab-bar-lines
becomes more than 1?

>> But even updating between 0 and 1 caused the problems.
>> We have bug#46557 created from https://debbugs.gnu.org/46299#119
>> I tried the test case from this bug report, and it doesn't fail anymore.
>> Do you think your patch fixed this old bug?
>
> You mean an init file with
>
> (set-frame-parameter nil 'tab-bar-lines 0)
> (set-frame-parameter nil 'tab-bar-lines 1)
> (set-frame-parameter nil 'tab-bar-lines 0)
>
> and doing C-x t 2?  I have never seen any problems with that so I can't
> tell.  But it's my experience that whatever we do to our frames, it's
> hard to break the external menu bar.

The bug was reproducible only on GNU/Linux, not on MS-Windows.