Michel:
The pre tags don't seem to work when wrapping XAML. Example (you'll probably need some way to see the raw source):

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <Style TargetType="Button">
            <Setter Property="Margin" Value="2"></Setter>
        </Style>
    </Window.Resources>
    <WrapPanel HorizontalAlignment="Left" Height="69"  VerticalAlignment="Top" Width="289">
        <Button Content="Button"/>
        <Button Content="Button"/>
        <Button Content="Button"/>
        <Button Content="Button"/>
    </WrapPanel>
</Window>

UPDATE: Did come thru OK - but not in preview ?