[C# Markup] items repeater inconsistent item types between Desktop and Windows

[kucint]

Create ItemsRepeater that is populated with items of type TextBlock

public MainPage()
{
    this
        .Background(ThemeResource.Get<Brush>("ApplicationPageBackgroundThemeBrush"))
        .Content(new StackPanel()
        .VerticalAlignment(VerticalAlignment.Center)
        .HorizontalAlignment(HorizontalAlignment.Center)
        .Children(
            new TextBlock()
            .HorizontalAlignment(HorizontalAlignment.Center)
            .Text("Hello Uno Platform!"),
            new ItemsRepeater()
            //.Layout(new StackLayout())  // works fine
            .Layout(new MyLayout())       // works fine, using my layout let me to inspect created items
            .HorizontalAlignment(HorizontalAlignment.Center)
            .ItemsSource(Enumerable.Range(0, 5))
            .ItemTemplate<int>(item =>
                new TextBlock()
                .HorizontalAlignment(HorizontalAlignment.Center)
                .Text(() => $"Item {item}"))
        ));
}

This works fine under Desktop and Windows, however in both cases created items differ.

Using my own layout let me to inspect created items:

public class MyLayout : NonVirtualizingLayout
{
    protected override Size MeasureOverride(NonVirtualizingLayoutContext context, Size availableSize)
    {
        double extentHeight = 0.0;
        double extentWidth = 0.0;
        foreach (UIElement element in context.Children)
        {
            element.Measure(availableSize);
            extentHeight += element.DesiredSize.Height;
            extentWidth = Math.Max(extentWidth, element.DesiredSize.Width);
        }

        return new Size(extentWidth, extentHeight);
    }

    protected override Size ArrangeOverride(NonVirtualizingLayoutContext context, Size finalSize)
    {
        double offset = 0.0;
        foreach (FrameworkElement element in context.Children.Cast<FrameworkElement>())
        {
            element.Arrange(new Rect(0, offset, element.DesiredSize.Width, element.DesiredSize.Height));
            offset += element.DesiredSize.Height;

            // inspect the type of element
            Debug.WriteLine($"element type: {element.GetType().Name}");
            Debug.WriteLine($"element.DataContext: {element.DataContext}");
        }

        return finalSize;
    }
}

Surprisingly the type of element differs between Desktop and Windows:

• Desktop : type is TextBlock as expected
• Windows: type is Grid. This grid contains one single element of type TextBlock which is the expected one.

The Grid is redundant under Windows, its origin is unknown. I do not use Grid in my code at all.

"Uno.Sdk": "5.4.0-dev.99"

repro: UnoNonVirtualizingLayoutWrongItemTypeApp.zip

[morning4coffe-dev]

@kucint Thank you for reporting this. I will have a look on the details.

[morning4coffe-dev]

@kucint I had a bit deeper look at this issue today and I can confirm this behavior is happening on the NonVirtualizingLayout, but only with C# Markup. Testing this with a similar layout using Xaml, this issue doesn't seem to reproduce. I opened an issue #2458 to track this further.