private void subscribeWatcher(ConstraintController constraintController) {
   ConstraintPanel view = constraintController.getView();
   if (!watcher.isWatched(view)) {
     watcher.register(view);
   }
   subscribeWatcherToConstraintTypeController(constraintController);
   constraintController.addConstraintListener(this);
 }
 private void subscribeWatcherToConstraintTypeController(
     ConstraintController constraintController) {
   ConstraintTypeController constraintTypeController =
       constraintController.getConstraintTypeController();
   if (constraintTypeController != null) {
     JPanel view = constraintTypeController.getView();
     if (!watcher.isWatched(view)) {
       watcher.register(view);
     }
   }
 }