abstract sclass DynSCP extends DynModule {
  transient SingleComponentPanel scp;
  transient ReliableSingleThread rstRevisualize2 = new(r revisualize2_impl);
  transient L<Runnable> afterVisualize2;
  static bool verbose;

  /*final*/ JComponent visualize() {
    scp = singleComponentPanel();
    scp.setComponent(visualize2());
    pcallFAll(afterVisualize2);
    ret scp;
  }
    
  void unvisualize() { scp = null; unvisualize2(); }
  JComponent visualize2() { null; }
  
  void unvisualize2() {} // overridable
  
  void revisualize2() {
    rstRevisualize2.trigger();
  }
  
  void revisualize2_impl() enter {
    //lock lock;
    if (scp == null) ret;
    JComponent c = visualize2();
    if (c != scp.getComponent()) {
      if (verbose) print("Setting component");
      scp.setComponent(c);
      pcallFAll(afterVisualize2);
    }
  }
  
  void setComponent(Component c) {
    if (scp != null) scp.setComponent(c);
  }
  
  // usually it'll be a JComponent
  JComponent getComponent() {
    ret scp == null ? null : (JComponent) scp.getComponent();
  }
  
  bool isShowing() { ret scp != null; }
  bool isShowing(Component c) { ret isComponentShowing(c); }
  
  void afterVisualize2(Runnable r) {
    afterVisualize2 = createOrAddToSyncList(afterVisualize2, r);
  }
}