sclass JCalculatedComponent<A extends JComponent> extends SingleComponentPanel is ChangeTriggerable {
  settable IF0<A> makeComponent;
  
  *(IF0<A> *makeComponent) {}
  
  transient ReliableSingleThread rstMakeComponent = new(-> {
    setComponent(makeComponent?!);
  });
  
  {
    bindToComponent(this, -> {
      if (!hasComponent()) rstMakeComponent.trigger();
    }, null);
  }

  public void change {
    rstMakeComponent.trigger();
  }
}