13.0-CURRENT oddity in output of dialog(1)

[Alan Somers]

On Sun, Feb 10, 2019 at 2:27 PM David Boyd <David.Boyd49 at twc.com> wrote:
>
> In 13.0-CURRENT, dialog(1) fills lines shorter than the box width with
> something other than the background color.  In an xterm session, the
> fill is white. In a console session, the fill is black.
>
> This appears to be a regression in the dialog(1) utility not seen in
> previous (11.2-RELEASE and 12.0-RELEASE) releases.
>
> To recreate:
>
> cat /etc/rc.conf | dialog --programbox 23 76
>
> No other problems have been observed in the dialog(1) utility.
>
> Thanks.
>
> David Boyd.

CC bapt at .  I've confirmed that the bug was introduced by r339488.
Unfortunately, that hardly narrows it down.  The diff is 49 kSLOC.
-Alan