@Override
  public void add(MutableTreeNode newChild) {
    super.add(newChild);
    boolean hasUnmarked = ((PackageDependenciesNode)newChild).hasUnmarked();
    boolean hasMarked = ((PackageDependenciesNode)newChild).hasMarked();
    updateMarked(hasUnmarked, hasMarked);
  }
@Override
  public void add(MutableTreeNode newChild)