code: protected int replace_s(int c_bra, int c_ket, String s)
      {
  	int adjustment = s.length() - (c_ket - c_bra);
  	current.replace(c_bra, c_ket, s);
  	limit += adjustment;
  	if (cursor >= c_ket) cursor += adjustment;
  	else if (cursor > c_bra) cursor = c_bra;
  	return adjustment;
      }
docs: /* to replace chars between c_bra and c_ket in current by the
  chars in s.