[RelativeSource] Inconsistency involving Self between Uno and Windows

[eriklimakc]

Current behavior

There is a different behavior between Windows and Uno.

Given the repo/example below RelativeSource as TemplatedParent works on Windows but not on Uno (fixed)
where RelativeSource as Self works on Uno but not on Windows.

Expected behavior

Same behavior in all platforms.

How to reproduce it (as minimally and precisely as possible)

Binding Sample Draft PR - unoplatform/Uno.Samples#681

Or

<Page.DataContext>
    <local:MainViewModel />
</Page.DataContext>

<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
    <ListView ItemsSource="{Binding Items}">
        <ListView.ItemTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal" Spacing="8">
                    <TextBlock VerticalAlignment="Center" Text="{Binding Text}" />

                    <!--  RelativeSource as TemplatedParent works on Windows but not on Uno  -->
                    <!--  RelativeSource as Self works on Uno but not on Windows  -->
                    <Button Command="{utu:ItemsControlBinding Path=DataContext.RemoveItemCommand}"
                            CommandParameter="{Binding DataContext, RelativeSource={RelativeSource Mode=Self}}"
                            Content="Delete" />

            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>
</StackPanel>

public partial class MainViewModel : ObservableObject
{
    [ObservableProperty]
    private ObservableCollection<Item> items;

    public ICommand RemoveItemCommand { get; }

    public MainViewModel()
    {
        Items =
        [
            new Item { Text = "Item 1" },
            new Item { Text = "Item 2" },
            new Item { Text = "Item 3" }
        ];

        RemoveItemCommand = new RelayCommand<Item>(RemoveItem, i => i is not null && Items.Contains(i));
    }

    private void RemoveItem(Item? item)
    {
        Items.Remove(item!);
    }
}

public class Item
{
    public string? Text { get; set; }
}

Works on UWP/WinUI

Yes

[eriklimakc]

#12732 Should fix this.

[agneszitte]

@jeromelaban, @MartinZikmund, @dansiegel (cc @Xiaoy312)
I will let you check the priority of this issue
Related PR: unoplatform/uno.extensions#2292

[MartinZikmund]

@morning4coffe-dev this may be fixed now with #17645 , can you check please?

[morning4coffe-dev]

@MartinZikmund, @Xiaoy312, @eriklimakc I can confirm that TemplatedParent as a source now works on Uno targets as well! 🎉

When I set it to Self, it still works on Uno only, not sure if we want to make some changes, to be inline with Windows.