title: How to set a specific header height for groupbox?
body: <p>As the title say, I need to know how can I set a specific header height for a GroupBox, suppose I've this:</p>
  
  <pre><code>&lt;GroupBox Header="Test"&gt;
  
  &lt;/GroupBox&gt;
  </code></pre>
  
  <p>this will display an header height based on the content of the header, but is possible also set a specific header height? How?
  Thanks.</p>