bug#61702: Minibuffer scrolling not working when long lines get truncated

[Eli Zaretskii]

> From: Johann Höchtl <johann.hoechtl@gmail.com>
> Date: Thu, 23 Feb 2023 08:12:09 +0100
> Cc: 61702@debbugs.gnu.org
> 
> emacs -Q
> M-x fido-vertical-mode
> M-x <consta> <-- any search term to narrow down the potential completions, in 
> this case 12 items remain
> matching
> narrow the whole emacs window so the search results have to "break" because 
> of long lines
> <down> <down> ... 
> The highlighted active line remains visible until the last items, than the 
> active line becomes invisible

Thanks.

It looks like the code in icomplete--render-vertical implicitly
assumes that every candidate takes just one screen line, which is
false in your scenario.  A workaround is to set truncate-lines non-nil
in the minibuffer.

João, can you take a look, please?