public void toggleFX(Model model, boolean on) {
    if (on) {
      for (MoteFX FX : statusFX) if (FX.mote.model() == model) return ;
      final MoteFX FX = new MoteFX(model.makeSprite()) ;
      statusFX.add(FX) ;
      FX.position.setTo(position) ;
      FX.position.z += high + 0.5f ;
      if (statusDisplayIndex < 0) statusDisplayIndex = 0 ;
    }
    else {
      int index = 0 ;
      for (MoteFX FX : statusFX) if (FX.mote.model() == model) {
        statusFX.remove(FX) ;
        if (statusDisplayIndex >= index) statusDisplayIndex-- ;
        return ;
      }
      else index++ ;
    }
  }