Stretching Content in an Expander Header (take two)

A while ago I posted a blog entry called Stretching Content in an Expander Header which discussed a way to make the content of an Expander’s header occupy all available space in the header area.  The solution I proposed back then required the use of some code to do the trick.  Today a fellow by the name of Patrick Jones posted a comment which shows a clean solution.  His solution still requires the use of code.

After reading over his sample I realized that it is possible (and easy) to implement the functionality without writing any code at all.  The original post has been updated to show the XAML-only solution, which I like the best out of all three options (if you do not care that the header element will be clipped on the righthand side).  Here’s the relevant XAML snippet:

<Expander>
  <Expander.Header>
    <TextBlock
      Text=”I am header text…”
      Background=”Blue”
      Width=”{Binding
        RelativeSource={RelativeSource
          Mode=FindAncestor,
          AncestorType={x:Type Expander}},
        Path=ActualWidth}”
      />
  </Expander.Header>
  <TextBlock Background=”Red”>
    I am some content…
  </TextBlock>
</Expander>

NOTE: Be sure to read the original post to learn about the limitations of this XAML-only approach, and when it is necessary to use the original technique.