<Grid
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Background="White"
  TextElement.FontSize="30"
  TextElement.Foreground="Black">

    <TextBlock Margin="20" TextWrapping="Wrap" TextTrimming="CharacterEllipsis" Background="Gray">
        <Bold>Lorem</Bold> ipsum <Italic>dolor</Italic> sit <Underline>amet</Underline>.
        <LineBreak/>
        <Bold FontWeight="Normal">Lorem <Span FontWeight="Bold">ipsum <Italic>sit <Underline>amet</Underline></Italic></Span></Bold>.
        <LineBreak/>
        <Span FontStyle="Italic"><Run Text="Named element bound text."/></Span>
        <LineBreak/>
        <Span FontWeight="Bold"><Run Text="DataContext bound text."/></Span>
    </TextBlock>
</Grid>