sclass AWTOnConceptChanges is AutoCloseable {
  settable JComponent component;
  settable Runnable action;
  settable Concepts concepts;
  settable int firstDelay;
  settable int delay = 500;
  
  long changes = -1;
  javax.swing.Timer timer;
  
  *(Concepts *concepts, JComponent *component, Runnable *action) {}
  
  void install {
    assertNotNull(concepts);
    
    timer = installTimer(component, delay, firstDelay, r _trigger);
  }
  
  void _trigger {
    long c = concepts.changes;
    if (changes != c) {
      changes = c;
      action?.run();
    }
  }
  
  close {
    dispose timer;
  }
}