<Window x:Class="BindingWithFallback.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="BindingWithFallback" Height="300" Width="300"
    >
    <StackPanel>
      <TextBox Text="{Binding Path=FastProperty, Mode=OneWay}" IsReadOnly="True" />
      <TextBox Text="{Binding Path=SlowProperty, Mode=OneWay, FallbackValue=(waiting), IsAsync=True}" IsReadOnly="True" />
      <TextBox Text="{Binding Path=NullProperty.FastProperty, Mode=OneWay, FallbackValue=(null)}" IsReadOnly="True" />
      <TextBox Text="{Binding Path=ExceptionProperty, Mode=OneWay, FallbackValue=(oops)}" IsReadOnly="True" />
    </StackPanel>
</Window>
