static <A extends JComponent> A bindToComponent(A component, Runnable onShow, Runnable onUnShow) {
  swing {
    final Var<Bool> flag = new(false);
    component.addAncestorListener(new AncestorListener {
      public void ancestorAdded(AncestorEvent event) {
        if (flag!) print("Warning: bindToComponent logic failure");
        flag.set(true);
        pcallF(onShow);
      }
  
      public void ancestorRemoved(AncestorEvent event) {
        if (!flag!) print("Warning: bindToComponent logic failure");
        flag.set(false);
        pcallF(onUnShow);
      }
  
      public void ancestorMoved(AncestorEvent event) {
      }
    });
    if (component.isShowing()) { // Hopefully this matches the AncestorListener logic
      flag.set(true);
      pcallF(onShow);
    }
  }
  ret component;
}

static <A extends JComponent> A bindToComponent(A component, Runnable onShow) {
  ret bindToComponent(component, onShow, null);
}

// passing a value from onShow to onUnShow
static <A extends JComponent, B> A bindToComponent(A component, IF0<B> onShow, IVF1<B> onUnShow) {
  new Var<B> b;
  ret bindToComponent(component,
    -> b.set(onShow!),
    -> { try { onUnShow.get(b!); } finally { b.set(null); } });
}