bug#56692: 29.0.50; scroll-bar in the minibuffer window disappears

[Eli Zaretskii]

> Cc: 56692@debbugs.gnu.org
> Date: Fri, 22 Jul 2022 19:53:59 +0800
> From:  Po Lu via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Visuwesh <visuweshm@gmail.com> writes:
> 
> > The exact details of this disappearance varies from my Emacs config
> > started as a daemon and emacs -Q.  To reproduce,
> >
> >         1. emacs -Q
> >         2. C-x 2
> >         3. Witness the disappearance.
> >         4. M-:
> >         5. Scroll-bar shows up again.
> >         6. C-x 0
> >         7. Scroll-bar shies away.
> 
> I fixed this on master but to be frank I don't know why it works, and
> why this call to move_it_to in set_vertical_scroll_bar makes the scroll
> bar not redeemed in inactive mini windows after redisplay_window ends:
> 
> --->    move_it_to (&it, -1, it.last_visible_x, window_box_height (w), -1,
>                     MOVE_TO_X | MOVE_TO_Y);

move_it_to was signaling an error in that case, that's why the scroll
bar didn't appear: the set_vertical_scroll_bar_hook method wasn't
called.

I fixed it now properly (I hope).  I guess it's one of those "TIL"
days...

> If anyone else can figure it out, I would be very grateful.

See the comment I added there, and if that's not clear enough, feel
free to ask.