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WinUI ListView ObservableColellection binding not working

I'm learning the new WinUI platform together with XAML and GUI programming in C# and I'm not sure if I correctly understand how the bindings and updates work, but I can't get the following code (minimal working example) to work:
MainPage.xaml
<Page
x:Class="uitest.MainPage"
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"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
<ListView ItemsSource="{x:Bind Items, Mode=OneWay}"></ListView>
<Button Content="Add" Click="Button_OnClick"></Button>
</StackPanel>
</Page>
MainPage.xaml.cs
using System.Collections.ObjectModel;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
namespace uitest
{
public sealed partial class MainPage : Page
{
public ObservableCollection<string> Items = new ObservableCollection<string>();
public MainPage()
{
this.InitializeComponent();
Items.Add("A");
Items.Add("B");
}
private void Button_OnClick(object sender, RoutedEventArgs e)
{
Items.Add("Next");
}
}
}
When I start the application, I see a list with two items but when I click the button nothing happens. I wanted to use the Live Visual Tree for debugging but it's not working for some reason.

I opened an issue on the official WinUI repository for this and apparently it's a compatibility fault in the latest WinUI 3 preview. I should also note this does not work only on the UWP platform but it works on the Desktop (Win32).

How to create child window by the context menu of page in wpf?

I have a context menu what is triggered by each list item of listbox.
And, I want to create child window when I select a context menu as below:
xaml
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Width="150" Orientation="Vertical" Margin="15, 5, 15, 5">
<StackPanel.ContextMenu>
<ContextMenu FontSize="16">
<MenuItem Header="{x:Static localRes:Resources.ID_STRING_SETTING}" Margin="5" Command="Setting_Click"/>
</ContextMenu>
It is already a sub page of main window.
So, I can't find a way how to set MainWindow instance as the owner of new window.
Behind Code
private void Setting_Click(object sender, RoutedEventArgs e)
{
SettingWindow SettingWindow = new SettingWindow();
SettingWindow.Owner = /* I do not know how to do */
SettingWindow.Show();
}

If your click command handler is in the code behind for your main window, then you need to set
deviceSettingWindow.Owner = this;
https://learn.microsoft.com/en-us/dotnet/api/system.windows.window.owner?view=netframework-4.8
Here's a small example. It includes a button with a handler whose code is in the code behind -
<Window x:Class="MainWindow.MainWindow"
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:ChildWindow"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Grid>
<Button Content="Button" HorizontalAlignment="Left" Margin="114,137,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>
</Grid>
</Window>
CodeBehind:
using System.Windows;
namespace MainWindow
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
var childWindow = new ChildWindow.Window1();
childWindow.Owner = this;
childWindow.Show();
}
}
}
Child Window - just an empty window
<Window x:Class="ChildWindow.Window1"
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:ChildWindow"
mc:Ignorable="d"
Title="Window1" Height="450" Width="800">
<Grid>
</Grid>
</Window>
Child Window Code Behind
using System.Windows;
namespace ChildWindow
{
/// <summary>
/// Interaction logic for Window1.xaml
/// </summary>
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
}
}
In my example, Since you are in the code behind for the MainWindow, this is a reference to the MainWindow, and setting 'childWindow.Owner = this' is setting the childWindow's owner to the MainWindow which is what I believe you want.
One thing that is a little confusing to me is that you are using a Command and a reference to an event handler in the code behind. I'm pretty sure that's not going to work. Commands need to Bind to an ICommand reference - you'll have to implement your own ICommand class, or use one from MVVM Light or another WPF MVVM Framework. Once you've got that you can pass a reference from the parent window through the Command as a CommandParameter. For an example of how to do this, see passing the current Window as a CommandParameter
If you are using an event handler on a control, then that can bind to the event handler implementation in the code behind like in my example. You need to choose one or the other.
If you're able to provide more details on how you're setup, it would make it easier for me to provide input on which way you need to go.

C# WPF Child Windows inside Main Window

So iv looked around for a bit and found out that MDI is obselete for WPF, Basically what i am trying to do is show a specific page in a grid object on load, and once a menu item from my drop down menu is selected, the content of the grid will be changed to the content from a different page (this is depending on which menu item is selected).
To go into more detail (perhaps this will help) The area where the window will be shown will need to have the window with no borders, or titles, or buttons to minimize/close etc.. only showing the content of this window, it won't be resizeable but fixed, i have a menu of which as i said earlier, when a different menu item is clicked, the relevant window should be displayed in the fixed area. Additionally if any buttons or events inside this content that is displayed happen (i.e a button causes a different window to show for example) then the content in the fixed area should be replaced by this new window's content
This is the first time i have done something like this and from what i've read it sounds like this is something very tricky for a WPF application, I hope i can get some sort of insight or direction i should be going so that i can make this possible.
Thanks.

You can try for example ChildWindow from Extended WPF Toolkit Community Edition.
Edit #1:
But whenever i try to create a WindowContainer in the Xaml it has
problems with the namespace prefix with "xctk:WindowContainer" so
how do i create the appropriate namespace prefix to use it?
You have to add that namespace:
xmlns:xctk=http://schemas.xceed.com/wpf/xaml/toolkit
For example:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
Title="MainWindow" Height="350" Width="525">
<Grid>
<xctk:WindowContainer>
<xctk:ChildWindow Height="100" Width="250" Left="10" Top="10">
<TextBlock Text="Hello World ..." />
</xctk:ChildWindow>
</xctk:WindowContainer>
</Grid>
</Window>
Edit #2:
You can of course change some properties (for example):
<xctk:ChildWindow
Height="100"
Width="250"
Left="10"
Top="10"
Name="chWindow"
CloseButtonVisibility="Hidden"
WindowStyle="None"
BorderThickness="0">
Edit #3:
Ok yeah, so with everything referenced it is giving me errors still..
Try it simple… Create Wpf Application, add Extended WPF Toolkit 2.4 NuGet package, in MainWindow.xaml add previous code and in MainWindow.xaml.cs add next code:
namespace WpfApplication1
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.Loaded += MainWindow_Loaded;
}
void MainWindow_Loaded(object sender, RoutedEventArgs e)
{
this.chWindow.Show();
}
}
}

How to use WinForms host in XAML file OR put it in Toolbox in WPF project

I've read tutorial how to embed Form in WPF's Window http://tech.pro/tutorial/786/wpf-tutorial-using-winforms-in-wpf I test it and it seems to be easy. But the problem is that I have create WinForm host programmatically in the .cs file. This is inconvienient to me.
I would like to put it in the XAML to have better control over its size. If it is possible I also would like to add WinForms host to toolbox

I am not sure why you would want to do that.. but anyhow because the Winform is a top-level control.
public partial class MainWindow : Window
{
Form1 frm = null;
public MainWindow()
{
InitializeComponent();
frm = new Form1();
frm.TopLevel = false;
}
private void frmMain_Loaded(object sender, RoutedEventArgs e)
{
myHost.Child = frm;
}
}
Happy Coding..
This is the accompany XAML...
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" WindowState="Maximized">
<Grid x:Name="frmMain" Background="{DynamicResource {x:Static SystemColors.ControlDarkBrushKey}}" Loaded="frmMain_Loaded">
<DockPanel LastChildFill="True">
<WindowsFormsHost x:Name="myHost" HorizontalAlignment="Stretch" Height="Auto" Margin="0" VerticalAlignment="Stretch" Width="Auto"/>
</DockPanel>
</Grid>
</Window>
Try it out... I assure you it works and..

Cannot drag text into a WPF window

I'm trying to set up a WPF window so that it can accept different types of data via Drag and Drop. If I make a new project and set the window to the following:
<Window x:Class="DropShare.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300" AllowDrop="True" DragEnter="Window_DragEnter">
<Grid>
</Grid>
</Window>
And set the code-behind to:
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
private void Window_DragEnter(object sender, DragEventArgs e)
{
}
}
I only ever get DragEnter firing for files. It never fires for anything else - text, images, etc.
Is there something I'm missing? All the tutorials I've read have seemed to suggest this is all that's needed as the DragEnter event handler let's me state what I accept.

So your code works fine for me. But try this...
In your Window:
<Label Background="Purple" HorizontalAlignment="Center" VerticalAlignment="Center" Content="Drag from here!" MouseDown="Label_MouseDown"/>
and in your code behind:
private void Label_MouseDown(object sender, MouseButtonEventArgs e)
{
DragDrop.DoDragDrop(this, "This is just a test", DragDropEffects.All);
}
Then drag from the label into the window and see if your event fires.
If this works, it may have something to do with the permissions level between Visual Studio and your outside environment (possibly).
See:
https://superuser.com/questions/59051/drag-and-drop-file-into-application-under-run-as-administrator

In WPF drag and drop feature always has to deal with DragDrop Class, Please check here how to do drag and drop across applications