Preserving whitespace in mixed content
<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" HorizontalAlignment="Center" VerticalAlignment="Center"> <TextBlock xml:space="preserve" Background="LightBlue"> A B <Run Text="A B" /> </TextBlock> </Page>