wchgat strips A_ALTCHARSET attrib; should it?

[Bill Gray]

   This "bug" (if it is one) cropped up in PDCursesMod,
which provides screen shots that should make the sort of
misbehavior obvious :

https://github.com/Bill-Gray/PDCursesMod/issues/192

   The same thing happens in ncurses.  As you can see in the
discussion at the above link,  we're unclear if this is the
specified behavior,  or if it's a for-real bug.  It is
certainly undesirable behavior,  but I don't want to "fix"
it in PDCursesMod if it's supposed to do that.

   I've posted a minimal example showing the bug at

https://www.projectpluto.com/temp/box.c

   Any opinion?

Thanks!          -- Bill