abstract sclass DynSCP extends DynModule {
  transient SingleComponentPanel scp;
  transient ReliableSingleThread rstRevisualize2 = new(r revisualize2_impl);
  
  /*final*/ JComponent visualize() { ret scp = singleComponentPanel(visualize2()); }
  void unvisualize() { scp = null; unvisualize2(); }
  JComponent visualize2() { null; }
  
  void unvisualize2() {} // overridable
  
  void revisualize2() {
    rstRevisualize2.trigger();
  }
  
  void revisualize2_impl() {
    lock lock;
    if (scp != null) scp.setComponent(visualize2());
  }
  
  void setComponent(JComponent c) {
    if (scp != null) scp.setComponent(c);
  }
  
  JComponent getComponent() {
    ret scp == null ? null : (JComponent) scp.getComponent();
  }
  
  bool isShowing() { ret scp != null; }
}