_mbvalid
extern int _mbinsshift(WINDOW *, int), _mbvalid(WINDOW *);
if (_scrmax > 1 && _mbvalid(win) == ERR)
if (_scrmax > 1 && (rv = _mbvalid(win)) == ERR)
if (_mbvalid(win) == ERR)
if (_mbvalid(win) == ERR)
if (_scrmax > 1 && (rv = _mbvalid(win)) == ERR)
if (_scrmax > 1 && _mbvalid(win) == ERR)