Right align last element on StackPanel

[tom-huntington]

HorizontalAlignment="Right" does not work in the following

<StackPanel Orientation="Horizontal" >
    <TextBlock VerticalAlignment="Center" Text="Enter Number"/>
    <NumberBox HorizontalAlignment="Right"/>
</StackPanel>

What do people do? Use a grid with

<Grid.ColumnDefinitions>
    <ColumnDefinition Width="*"/>
    <ColumnDefinition Width="auto"/>
</Grid.ColumnDefinitions>