title: WPF GroupBox with no header space
body: <p>Easy one, I would like to have a GroupBox with no header space</p>
  <p>The closest thing is a border, but the border &quot;by default&quot; does not have the same Style as the group box.</p>
  <p>What's the easiest way (least xaml / code) to get the desired GroupBox ?</p>
  <p>Thanks</p>