@Command 
	//@NotifyChange("selectedTodo") //use postNotifyChange() to notify dynamically
	public void deleteTodo(@BindingParam("todo") Todo todo){
		//save data
		todoListService.deleteTodo(todo);
		
		//update the model, by using ListModelList, you don't need to notify todoListModel change
		todoListModel.remove(todo);
		
		if(todo.equals(selectedTodo)){
			//refresh selected todo view
			selectedTodo = null;
			//for the case that notification is decided dynamically
			BindUtils.postNotifyChange(null, null, this, "selectedTodo");
		}
	}