public void incColonists(Object args[]) {
    final Background b = (Background) args[0] ;
    final int
      inc = (Integer) args[1],
      index = Visit.indexOf(b, COLONIST_BACKGROUNDS) ;
    int amount = colonists[index], total = 0 ;
    for (int i : colonists) total += i ;
    if (inc < 0 && amount <= 0) return ;
    if (inc > 0 && total >= MAX_COLONISTS) return ;
    colonists[index] += inc ;
    configForLanding(null) ;
  }