DataGrid control not working when using XAML islands in a Win32 app

[Iordan-Iulian-Bogdan]

Describe the bug

DataGrid control not working when using XAML islands, adding a DataGrid control to be used with a XAML island from a C# Class Library in a Win32 project wont show up, the code compiles and runs fine except the control is not visible. Is it possible I am missing something ?

For instance adding this in a user control :

        <controls:DataGrid x:Name="nameGrid"
                   AutoGenerateColumns="False"
                   Margin="0,0,0,10"
                   Width="600"
                   HeadersVisibility="Column"
                   GridLinesVisibility="Horizontal"
                   IsReadOnly="True">
            <controls:DataGrid.Columns>
                <controls:DataGridTextColumn Header="ID" Binding="{Binding Id}" Width="SizeToHeader"/>
                <controls:DataGridTextColumn Header="First Name" Binding="{Binding FirstName}" Width="*"/>
                <controls:DataGridTextColumn Header="Last Name" Binding="{Binding LastName}" Width="*"/>
                <controls:DataGridTextColumn Header="Address" Binding="{Binding Address}" Width="2*"/>
            </controls:DataGrid.Columns>
        </controls:DataGrid>

Then in my function which gets called by the Win32 app where I am creating a new window from my SampleWindow which contains the DataGrid results in a blank window.

        #pragma warning disable IDE0060
        public static int ShowWindow(nint args, int sizeBytes)
        {
        #pragma warning restore IDE0060

            if (!Bootstrap.TryInitialize(0x00010007, string.Empty, new PackageVersion(), Bootstrap.InitializeOptions.None, out var hr) &&
                !Bootstrap.TryInitialize(0x00010006, string.Empty, new PackageVersion(), Bootstrap.InitializeOptions.OnNoMatch_ShowUI, out hr))
                return hr;

            if (_app == null)
            {
                _app = new DummyApp(); // Optional: enables WinUI styles
                DispatcherQueueController.CreateOnCurrentThread();
            }

            var _source = new DesktopWindowXamlSource();
            _source.Initialize(Win32Interop.GetWindowIdFromWindow(args));

            var window = new SampleWindow(); 
            window.Title = "People Table";
            window.Activate();

            return 0;
        }

Steps to reproduce

1. Add a DataGrid control in a User Control in a C# Class library.
2. Use it in a XAML island in a Win32 app.
3. Control wont show up.

Expected behavior

DataGrid control is visible.

Screenshots

How it looks when not using XAML island :

How it looks from a XAML island :

Code Platform

• UWP
• WinAppSDK / WinUI 3
• Web Assembly (WASM)
• Android
• iOS
• MacOS
• Linux / GTK

Windows Build Number

• Windows 10 1809 (Build 17763)
• Windows 10 1903 (Build 18362)
• Windows 10 1909 (Build 18363)
• Windows 10 2004 (Build 19041)
• Windows 10 20H2 (Build 19042)
• Windows 10 21H1 (Build 19043)
• Windows 10 21H2 (Build 19044)
• Windows 10 22H2 (Build 19045)
• Windows 11 21H2 (Build 22000)
• Other (specify)

Other Windows Build number

No response

App minimum and target SDK version

• Windows 10, version 1809 (Build 17763)
• Windows 10, version 1903 (Build 18362)
• Windows 10, version 1909 (Build 18363)
• Windows 10, version 2004 (Build 19041)
• Windows 10, version 2104 (Build 20348)
• Windows 11, version 22H2 (Build 22000)
• Other (specify)

Other SDK version

No response

Visual Studio Version

No response

Visual Studio Build Number

No response

Device form factor

No response

Additional context

No response

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