@Override
  public int compare(NodeDescriptor obj1, NodeDescriptor obj2){
    final int weight1 = obj1.getWeight();
    final int weight2 = obj2.getWeight();
    if (weight1 != weight2) return weight1 - weight2;
    if (obj1 instanceof ProjectViewNode && obj2 instanceof ProjectViewNode) {
      return ((ProjectViewNode<?>)obj1).getTitle().compareToIgnoreCase(((ProjectViewNode<?>)obj2).getTitle());
    }
    if (obj1 instanceof ModuleToDoNode && obj2 instanceof ModuleToDoNode){
      return ((ModuleToDoNode)obj1).getValue().getName().compareToIgnoreCase(((ModuleToDoNode)obj2).getValue().getName());
    } else if(obj1 instanceof ModuleToDoNode) {
      return -1;
    } else if(obj2 instanceof ModuleToDoNode) {
      return 1;
    } else{
      throw new IllegalArgumentException(obj1.getClass().getName()+","+obj2.getClass().getName());
    }
  }
@Override
  public int compare(NodeDescriptor obj1, NodeDescriptor obj2)