WPF-取消选择TabControl中的选项卡会导致问题

Question

I have an application with some TabControl, and in a specific tab a long computation can be started. I want the user to confirm leaving the tab and aborting the computation. So far, I created a Behavior and attached it to the tabcontrol. (code at the end). My problem: suppose I want to conifrm leaving tab #3. I choose tab #2 -> confirmation dialog pops and I choose no (CanNavigateFromMe() == false), and I return to tab #3. Again, I choose tab #2 and get same behavior. I want to choose it for the 3rd time - now, clicking the header does not fire the CurrentChanging event!

code for the behavior:

    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.Loaded += new System.Windows.RoutedEventHandler(AssociatedObject_Loaded);
    }

    void AssociatedObject_Loaded(object sender, System.Windows.RoutedEventArgs e)
    {
        // required in order to get CurrentItemChanging
        AssociatedObject.IsSynchronizedWithCurrentItem = true;

        AssociatedObject.Items.CurrentChanging += new CurrentChangingEventHandler(Items_CurrentChanging);
    }



    void Items_CurrentChanging(object sender, CurrentChangingEventArgs e)
    {
        var item = ((ICollectionView)sender).CurrentItem;

        var view = item as FrameworkElement;
        if (view == null)
        {
            return;
        }
        IAllowNavigation allowNavigation = view.DataContext as IAllowNavigation;
        if ((allowNavigation != null) &&
            (allowNavigation.CanNavigateFromMe() == false))
        {
            e.Cancel = true;
            AssociatedObject.SelectedItem = view;
        }
    }

Answer 1

After some help from friends, I found out I needed to: 1. call Refresh() on the collection if cancelling the selection. 2. ensure the original selection is made if I decide to allow the selection (this involves user input and takes time, meanwhile ecents inside other tabs can change the selected item)

    void Items_CurrentChanging(object sender, CurrentChangingEventArgs e)
    {
        var newItem = AssociatedObject.SelectedItem;
        var item = ((ICollectionView)sender).CurrentItem;


        var view = item as FrameworkElement;
        if (view == null)
        {
            return;
        }
        IAllowNavigation allowNavigation = view.DataContext as IAllowNavigation;
        if ((allowNavigation != null) &&
            (allowNavigation.CanNavigateFromMe() == false))
        {
            e.Cancel = true;
            AssociatedObject.SelectedItem = view;

        }
        else
        {
            AssociatedObject.SelectedItem = newItem;
        }

        ((ICollectionView)sender).Refresh();

    }