private void DataContextChangedEventHandler(object sender, DependencyPropertyChangedEventArgs e)
        {
            if (DataContext != null && DataContext is ProductBacklogViewModel)
            {
                _viewModel = DataContext as ProductBacklogViewModel;
                _viewModel.PropertyChanged += ViewModelPropertyChangedEventHandler;

                RefreshErrorMessageDialogVisibility();
                RefreshStoryDialogVisibility();
                RefreshRemoveStoryConfirmationDialogVisibility();
            }
        }
        public ProductBacklog()
        {
            InitializeComponent();

            if (DataContext is ProductBacklogViewModel)
            {
                _viewModel = DataContext as ProductBacklogViewModel;
                _viewModel.PropertyChanged += ViewModelPropertyChangedEventHandler;

                RefreshErrorMessageDialogVisibility();
                RefreshStoryDialogVisibility();
                RefreshRemoveStoryConfirmationDialogVisibility();
            }
            else
            {
                DataContextChanged += new DependencyPropertyChangedEventHandler(DataContextChangedEventHandler);
            }
        }