Avalonia/samples/Sandbox/MainWindow.axaml

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
        x:Class="Sandbox.MainWindow">
        
        <ScrollViewer>
                <StackPanel>
                        <Button Margin="0 100000000000000000 0 0">0</Button>
                        <Button>1</Button>
                </StackPanel>
        </ScrollViewer>
</Window>