bug#69093: window-state-put doesn't update current buffer

[Drew Adams <drew.adams@oracle.com>]

> note that multi-frame setups got more and more
> broken since Emacs 26

Yes.  Unfortunately the passive voice is needed
here because much has changed without our being
able to identify and say who/what changed what.

> and are maybe not used frequently nowadays.

They _never_ were frequently used.  They were
standard in Epoch, but never integrated into
GNU Emacs OOTB.  GNU Emacs users of them have
always been outliers.  Dunno whether Stefan M
still uses a standalone minibuffer.  If not,
I might be the only user who does.

> So you probably needn't give them much
> attention in the first place.

That's the problem in the first place, and IMO
the reason they've never been used frequently.
Emacs developers don't, themselves, use them,
and so don't test changes against them,...
Vicious circle.  Too bad.

(No, I don't have the time anymore to try to
track down what might have broken what & when.
Just saying that this is unfortunate.  Things
might have been different if GNU Emacs had,
many moon ago, provided a standalone minibuffer
OOTB, a la Epoch.)