title: Preventing a WPF Expander from expanding when header is clicked
body: <p>How can I prevent a WPF <a href="http://msdn.microsoft.com/en-us/library/system.windows.controls.expander.aspx" rel="noreferrer"><code>Expander</code></a> from expanding when its header is clicked? I would like my <code>Expander</code> to expand or collapse only when the expand button itself is clicked.</p>
  
  <p>I imagine the answer has something to do with canceling a bubbled event. If possible I would like to implement the solution in XAML while avoiding retemplating the entire <code>Expander</code>.</p>