WPF Caliburn Micro Notify Property Change not updating UI in ShellView

Question

I created a new C# WPF project based on https://www.codemag.com/Article/1905031/A-Design-Pattern-for-Building-WPF-Business-Applications-Part-1 with Caliburn Micro and Windsor Castle based on .NET 7.0 as target framework. The Problem is: None of the Property Changes is updating the UI (The ugly gray InfoMessageArea should be hidden and a Text should appear while starting the App - as well as the WindowTitle that should reflect a change to "Test"). What am I missing here? The left list box correctly loads the implemented Modules using Windsor Castle, but the basic binding stuff is not working. And I would appreciate if anybody has an idea how the content of the window would "stretch" to full window's size as a side node. I created a new ShellView, that is acting as the Main Window of the application. The ShellViewModel derives from Conductor which has an ancestor Caliburn.Micro.PropertyChangedBase implementing INotifyPropertyChangedEx. The ShellView.xaml code is as follows:

<Window x:Class="BM.App.Views.ShellView"
    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:vm="clr-namespace:BM.App.ViewModels"
    xmlns:local="clr-namespace:BM.App.Views"
    mc:Ignorable="d"
    d:DataContext="{x:Type vm:ShellViewModel}"
    Title="{Binding WindowTitle}"
    Height="450" Width="800"
    WindowStartupLocation="CenterScreen"
    Loaded="Window_Loaded">
<Window.Resources>
    <vm:ShellViewModel x:Key="viewModel" 
                      InfoMessageTitle="Please Wait While Loading Application..."
                      InfoMessage="Sample of Business Application Screens" />
</Window.Resources>

<Grid Style="{StaticResource contentAreaStyle}">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="200"/>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition Height="auto"/>
        <RowDefinition Height="20"/>
    </Grid.RowDefinitions>

    <ListBox x:Name="MenuItems" DisplayMemberPath="Caption" Grid.Column="0"/>

    <ContentControl x:Name="CurrentView" Grid.Row="0" Grid.Column="1" Margin="2"/>

    <!-- Informational Message Area -->
    <Border Grid.Row="0" Grid.Column="1" Grid.ColumnSpan="1" Panel.ZIndex="2"
        Visibility="{Binding Path=IsInfoMessageVisible, Converter={StaticResource visibilityConverter}}" Style="{StaticResource infoMessageArea}">
        <StackPanel>
            <TextBlock FontSize="20" Text="{Binding Path=InfoMessageTitle}" />
            <TextBlock FontSize="12" Text="{Binding Path=InfoMessage}" />
        </StackPanel>
    </Border>

    <StatusBar x:Name="stbMain" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" MinWidth="500"></StatusBar>

</Grid>

The ShellView.xaml.cs as follows:

    public partial class ShellView : Window
{
    // Main window's view model class
    private ShellViewModel _viewModel;

    public ShellView()
    {
        InitializeComponent();
        // Connect to instance of the view model created by the XAML
        _viewModel = (ShellViewModel)this.Resources["viewModel"];
    }

    private async void Window_Loaded(object sender, RoutedEventArgs e)
    {
        await LoadApplication();

        // Turn off informational message area
        _viewModel.ClearInfoMessages();
    }

    public async Task LoadApplication()
    {
        // INFO: This text is not visible in the InfoMessage Area
        _viewModel.InfoMessage = "Loading application (method 1)...";

        //INFO: the 5 seconds delay are successfully invoked.
        //TODO: Load Stuff...
        await Dispatcher.BeginInvoke(new Action(() => {
            System.Threading.Thread.Sleep(5000);
        }), DispatcherPriority.Background);

        // INFO: Test will not be visible in the application's window!
        _viewModel.WindowTitle = "Test";

        // INFO: Neither Refresh() is updating the UI.
        _viewModel.Refresh();

        await Task.CompletedTask;
    }
}

The ShellViewModel.cs Code:

using BM.Contracts; 
using Caliburn.Micro; 
using System.Collections.ObjectModel; 
using System.Windows.Input; 
namespace BM.App.ViewModels 
{
    public class ShellViewModel : Conductor<object>
    {
        public ObservableCollection<ViewModelBase> OpenTabs { get; private set; } = new ObservableCollection<ViewModelBase>();

        public ObservableCollection<ShellMenuItem> MenuItems { get; private set; } = new ObservableCollection<ShellMenuItem>();

        private const string WindowTitleDefault = "mp Beleg Matching (LF | DATEV | SB)";
        private string _windowTitle = WindowTitleDefault;

        public ShellViewModel()
        {
            MenuItems = new ObservableCollection<ShellMenuItem>();
            AddTabCommand = null;
            CloseTabCommand = null;
            _selectedMenuItem = null;
        }
        ICommand AddTabCommand;
        ICommand CloseTabCommand;
        private bool _IsInfoMessageVisible = true;
        private string _InfoMessageTitle = string.Empty;
        private string _InfoMessage = string.Empty;

        public bool IsInfoMessageVisible
        {
            get { return _IsInfoMessageVisible; }
            set
            {
                _IsInfoMessageVisible = value;
                NotifyOfPropertyChange("IsInfoMessageVisible");
            }
        }

        public string InfoMessage
        {
            get { return _InfoMessage; }
            set
            {
                _InfoMessage = value;
                if (!_IsInfoMessageVisible && !string.IsNullOrEmpty(value))
                {
                    IsInfoMessageVisible = true;
                }
                NotifyOfPropertyChange("InfoMessage");
            }
        }

        public string InfoMessageTitle
        {
            get { return _InfoMessageTitle; }
            set
            {
                _InfoMessageTitle = value;
                NotifyOfPropertyChange("InfoMessageTitle");
            }
        }

        public void ClearInfoMessages()
        {
            InfoMessage = string.Empty;
            InfoMessageTitle = string.Empty;
            IsInfoMessageVisible = false;
        }

        public string WindowTitle
        {
            get { return _windowTitle; }
            set
            {
                _windowTitle = value;
                NotifyOfPropertyChange(() => WindowTitle);
            }
        }


        private ShellMenuItem _selectedMenuItem;

        public ShellMenuItem SelectedMenuItem
        {
            get { return _selectedMenuItem; }
            set
            {
                if (_selectedMenuItem == value)
                    return;
                _selectedMenuItem = value;
                NotifyOfPropertyChange(() => SelectedMenuItem);
                NotifyOfPropertyChange(() => CurrentView);
            }
        }

        public object? CurrentView
        {
            get { return _selectedMenuItem?.ScreenViewModel; }
        }
    }
}

Answer 1

You do a mixture with code behind and MVVM. If you are using Caliburn, use MVVM. Castle Windsor is a container, so i dont know, i am using Ninject and Caliburn (last version).

Sample to display a splash screen during 3 sec and change the title of ShellViewModel: just create a WPF .NET project then:

Modify App.xaml:

<Application x:Class="WpfApp2.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:WpfApp2">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary>
                    <local:Bootstrapper x:Key="Bootstrapper" />
                </ResourceDictionary>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>

---

Bootsrapper.cs:

using Caliburn.Micro;
using Ninject;
using System;
using System.Collections.Generic;
using System.Windows;

namespace WpfApp2
{
    public class Bootstrapper : BootstrapperBase
    {
        private IKernel kernel;
        public Bootstrapper() //Constructor
        {
            Initialize();
        }
        protected override void Configure()
        {
            //Bind all views or tools to container
            kernel = new StandardKernel();
            kernel.Bind<IWindowManager>().To<WindowManager>().InSingletonScope();
            kernel.Bind<IEventAggregator>().To<EventAggregator>().InSingletonScope();
            kernel.Bind<SplashViewModel>().ToSelf().InSingletonScope();
            kernel.Bind<ShellViewModel>().ToSelf().InSingletonScope();
        }
        //Override the startup method and launch the shell instead
        protected override async void OnStartup(object sender, StartupEventArgs e)
        {
            var wm = kernel.Get<WindowManager>();
            var vm = kernel.Get<SplashViewModel>();
            //Load the  splash screen
            await wm.ShowWindowAsync(vm);
            
            //Load the ShellView
            await DisplayRootViewForAsync<ShellViewModel>();

        }
        protected override object GetInstance(Type service, string key)
        {
            return kernel.Get(service);
        }

        protected override IEnumerable<object> GetAllInstances(Type service)
        {
            return kernel.GetAll(service);
        }
    }
}

---

SplashView.xaml:

<Window x:Class="WpfApp2.SplashView"
        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:local="clr-namespace:WpfApp2"
        mc:Ignorable="d" WindowStartupLocation="CenterScreen" WindowStyle="None"
        Title="SplashView" Height="100" Width="800">
    <Grid>
        <TextBox x:Name="Info" HorizontalContentAlignment="Center" VerticalContentAlignment="Center"
                 FontWeight="ExtraBold" FontSize="20" Foreground="Blue" IsReadOnly="True"/>
    </Grid>
</Window>

---

SplashViewModel.cs

using Caliburn.Micro;
using System.Threading;
using System.Threading.Tasks;

namespace WpfApp2
{
    public class SplashViewModel : Screen, IHandle<string>
    {
        public string Info { get; set; }
        public SplashViewModel(IEventAggregator eventAggregator)
        {
            Info = "Loading application (method 1)...";
            eventAggregator.SubscribeOnPublishedThread(this);
        }

        public async Task HandleAsync(string message, CancellationToken cancellationToken)
        {
            //Message received, wait 3 sec before to close the Splash Screen
            await Task.Delay(3000);
            if(message.Equals("End"))
                await TryCloseAsync();
        }
    }
}

---

ShellView.xaml

<Window x:Class="WpfApp2.ShellView"
        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:local="clr-namespace:WpfApp2"
        mc:Ignorable="d" WindowStartupLocation="CenterScreen"
        Height="450" Width="800">
    <Grid>
        <TextBox Name="Info2" Width="300" Height="70" Background="Aquamarine" />
    </Grid>
</Window>

---

And finally ShellViewModel.cs

using Caliburn.Micro;
using System.Threading;
using System.Threading.Tasks;

namespace WpfApp2
{
    public class ShellViewModel : Screen
    {
        public IEventAggregator eventAggregator;

        public ShellViewModel(IEventAggregator eventAggregator)
        {
            this.eventAggregator = eventAggregator;
            //Change the title of view
            DisplayName = "TEST";
            Info2 = $"View {DisplayName} Loaded!!";
        }
        protected override async Task OnInitializeAsync(CancellationToken c)
        {
            //Publish a string message to close the Splash Screen
            await eventAggregator.PublishOnUIThreadAsync("End");
        }

        private string info2;
        public string Info2
        {
            get
            {
                return info2;
            }
            set
            {
                info2 = value;
                NotifyOfPropertyChange(() => Info2);
            }
        }
    }
}

Answer 2

So, after investigating quite some time, I found the solution to my problem. Hope this will help some other desperate souls out there, having the same binding problems:

I added the DataContext attribute to the Grid of the ShellView's XAML:

    <Grid Style="{StaticResource contentAreaStyle}"
      DataContext="{StaticResource viewModel}">

and instantly the Binding was working. What I also figured out: The Intellisense (Jump to Declaration/F12) didn't work on my bound properties. After adding the DataContext to the Grid it "magically" worked out (eg. hitting F12 on IsInfoMessageVisible jumped to the definition of the ViewModel). I am not an expert in WPF, so I wouldn't have come to the idea to add the DataContext a second time to a child control a second time if I even had a DataContext bound to the Window's container. May be one of you have some ideas to fill the gap between my ears :-).