ActualHeight binding does not update

Question

I am trying to set up a binding to the ActualHeight of a FrameworkElement. It only seems to update once, but never updates after that. I tested this in a simple silverlight application with this markup, and it doesn't update when the browser window is resized. If I hook the LayoutUpdated, you can see that the ActualHeight is changing, but it is not updating the binding.

<Grid x:Name="LayoutRoot" Background="White">
    <TextBlock Text="{Binding ActualHeight, ElementName=LayoutRoot}" />
</Grid>

Shouldn't I be able to bind to ActualHeight?