Interaction MahappDialog Confirm Delete

[Allgauer77]

Hello forum,

I am working with WPF .NET6 and I am trying to create a MahApp dialog for a delete confirmation using ReactiveUI / ReactiveCommand/ Interaction.

I have Kent's book and want to include example 1 with chapter09.

When I delete, the following message is generated in the class.

System.InvalidCastException: "Unable to cast object of type 'System.Windows.Navigation.NavigationWindow' to type 'MahApps.Metro.Controls.MetroWindow'."

Please for help.
Thanks

public static class UserControlExtensions
{
public static IObservable ShowMessage(
this UserControl @this,
string title,
string message,
MessageDialogStyle style = MessageDialogStyle.Affirmative,
MetroDialogSettings settings = null)
{
var window = (MetroWindow)Window.GetWindow(@this);
return window
.ShowMessageAsync(title, message, style, settings)
.ToObservable();
}
}

<rxui:ReactiveUserControl

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    
    xmlns:cv="clr-namespace:CMO.Global.Converter" 
   
   
    xmlns:system="clr-namespace:System;assembly=mscorlib"

    xmlns:cmo.global="clr-namespace:CMO.Global"
  

    xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
    xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
    xmlns:dxb="http://schemas.devexpress.com/winfx/2008/xaml/bars"
    xmlns:dxmvvm="http://schemas.devexpress.com/winfx/2008/xaml/mvvm"
    xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors"
        
    xmlns:vm="clr-namespace:CMO.Articles"
     
    xmlns:rxui="http://reactiveui.net"
    x:TypeArguments="vm:ArticleMainViewModel"


    xmlns:ma="http://metro.mahapps.com/winfx/xaml/controls"


    x:Class="CMO.ArticleView"

    mc:Ignorable="d" 
    Height="auto" Width="auto" 
    
>

public partial class ArticleView : ReactiveUserControl
{

    public ArticleView()
    {
        InitializeComponent();
        //DataContext = new CMO.Articles.ArticleMainViewModel();  // Datacontext für XAML Binding



        ViewModel = new ArticleMainViewModel(); // Typsicheres Binding Reactive UI



        this
            .WhenActivated(
                disposableRegistration =>
                {

                    this.WhenAnyValue(vm => vm.ViewModel).BindTo(this, v => v.DataContext)
                    .DisposeWith(disposableRegistration);



                    this
                        .OneWayBind(this.ViewModel, vm => vm.MyListBindable, v => v.ArticleGridControl.ItemsSource)
                        .DisposeWith(disposableRegistration);




                    Observable.FromEventPattern(ArticleGridControl, "SelectedItemChanged").Select(_ => ArticleGridControl.SelectedItem).BindTo(ViewModel, vm => vm.SelectedItem);








                    this
                        .BindCommand(this.ViewModel, vm => vm.DeleteArticleCommand, v => v.deleteArticleButton)
                        .DisposeWith(disposableRegistration);


                    this
                        .BindCommand(this.ViewModel, vm => vm.LoadArticleCommand, v => v.loadArticleButton)
                        .DisposeWith(disposableRegistration);



                    this
                       .ViewModel
                       .ConfirmDeleteArticle
                       .RegisterHandler(
                           context =>
                               this
                                   .ShowMessage("Confirm Delete", $"Are you sure you want to delete '{context.Input}'?", MessageDialogStyle.AffirmativeAndNegative)
                                   .Do(result => context.SetOutput(result == MessageDialogResult.Affirmative)))
                       .DisposeWith(disposableRegistration);



                });

    }



}

public static class UserControlExtensions
{
    public static IObservable<MessageDialogResult> ShowMessage(
        this UserControl @this,
        string title,
        string message,
        MessageDialogStyle style = MessageDialogStyle.Affirmative,
        MetroDialogSettings settings = null)
    {
        var window = (MetroWindow)Window.GetWindow(@this);
        return window
            .ShowMessageAsync(title, message, style, settings)
            .ToObservable();
    }
}

}

public class ArticleMainViewModel : ReactiveObject, IDisposable
{

    private readonly IDisposable _cleanUp;


    public IObservableCollection<ArticleViewModel> MyListBindable { get; set; } = new ObservableCollectionExtended<ArticleViewModel>();
    private readonly SourceList<ArticleViewModel> sourceList = new SourceList<ArticleViewModel>();



    private readonly ReactiveCommand<Unit, Unit> deleteArticleCommand;
    public ReactiveCommand<Unit, Unit> DeleteArticleCommand => this.deleteArticleCommand;



    private readonly ReactiveCommand<Unit, Unit> loadArticleCommand;
    public ReactiveCommand<Unit, Unit> LoadArticleCommand => this.loadArticleCommand;



    private readonly Interaction<ArticleViewModel, bool> confirmDeleteArticle;
    public Interaction<ArticleViewModel, bool> ConfirmDeleteArticle => this.confirmDeleteArticle;







    #region Konstruktor

    public ArticleMainViewModel()
    {


        this.confirmDeleteArticle = new Interaction<ArticleViewModel, bool>();




        var listLoader = sourceList.Connect()
           .Sort(SortExpressionComparer<ArticleViewModel>.Ascending(vm => vm.ArticleId))
           .ObserveOnDispatcher()
           .Bind(this.MyListBindable)
           .Subscribe();





       
        var listarticleIsChanged = sourceList.Connect()
            .AutoRefresh()
            .Filter(filter => filter.ArticleIsChanged) // Filtern nach ArticleIsChanged
            .Publish();

        _cleanUp = new CompositeDisposable(sourceList,
            listLoader,
            listarticleIsChanged.Count().Subscribe(count => CountArticleIsChanged = count),
            listarticleIsChanged.Connect()
            );






       
        var listAllDataSets = sourceList.Connect()
            .Publish();  

       _cleanUp = new CompositeDisposable(sourceList,
           listLoader,
           listAllDataSets.Count().Subscribe(count => CountALlDataSets = count),
           listAllDataSets.Connect()
           );



        lock (_listLock)
        {
            ArticlesListCollectionView = new ListCollectionView((System.Collections.IList)MyListBindable);
        }






      


        var canArticleDelete = this
         .WhenAnyValue(x => x.SelectedItem)
         .Select(selectedItem => selectedItem != null);


        


        this.deleteArticleCommand = ReactiveCommand.CreateFromObservable(
           () =>
               this
                   .confirmDeleteArticle
                   .Handle(this.SelectedItem)
                   .Where(result => result)
                   .Select(_ => Unit.Default)
                   .ObserveOn(RxApp.MainThreadScheduler)
                   .Do(_ => DeleteArticleExecuted()),
           canArticleDelete);