bug#66128: 28.2; visible-bell breaks setterm --inversescreen on

[Eli Zaretskii]

> From: tom@logand.com
> Date: Wed, 20 Sep 2023 22:14:49 +0200
> 
> 
> 
> in black linux console:
> 
>    $ setterm --inversescreen on
> 
> after that, in white linux console:
> 
>    $ emacs -Q --eval '(setq visible-bell t)'
> 
> all looks fine, emacs background is white
> now press page-up key to trigger visual bell
> and suddenly emacs background is black
> visual bell should preserve terminal colors

Emacs just sends to the terminal the sequence defined by the "vb"
termcap capability.  Is that not correct when the screen colors are
inverted?  Is this perhaps the problem of the terminal?

Btw, we always use the termcap's "vb", even when terminfo is
available; should we use the terminfo's "flash" instead?