lib/53653: Curses doesn't always show line drawing characters correctly on wsvt25

[uwe%NetBSD.org@localhost]

>Number:         53653
>Category:       lib
>Synopsis:       Curses doesn't always show line drawing characters correctly on wsvt25
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Oct 07 01:55:00 +0000 2018
>Originator:     Valery Ushakov
>Release:        NetBSD 8.99.25
>Organization:
>Environment:
>Description:
Use misc/dialog with TERM=wsvt25 and observe ASC ascii chars instead
of line-drawing chars shown in some boxes.  Works with TERM=xterm.  As
far as I can tell the problem is when colors are switched in the
middle of using line-drawing characters.  dialog tries to create faux
3d look by using colors, and when color is changed in the middle of
the line, the line after the color switch comes out in ASCII.

For the top border the following is emitted with wsvt25, cleaned up
and split for readability:

    \E[37m\E[47m\E(0lqqq\E[m\E(B
    \E[30m\E[47mk\E(B

Note that for the upper-right corner 'k' there's no preceding smacs
\E[(0 sequence, so I guess curses thinks it's still in ACS mode, while
it's not (it emitted rmacs \E(B before just before the color switch).

>How-To-Repeat:
On wscons run:

   TERM=wsvt25 dialog --msgbox "hello world" 10 40

cf.

  TERM=xterm dialog --msgbox "hello world" 10 40 # works

>Fix: