title: WPF ItemsControl ItemTemplate border with GroupStyle
body: <p>This is the first time I've posted a pic, so hopefully it turns out well (a picture is worth a thousand words, and I don't want to type a thousand words). But, the image below is what I'm trying to accomplish.</p>
  
  <p>I have a collection of objects that I'm needing grouped by property "Group". I'm using a CollectionViewSource that is bound to my data source that is doing the grouping for me.</p>
  
  <p>I'm using an ItemsControl control (but could easily use another control) to display this information. I'm able to group the information by the property but I'd like to be able to surround the entire group with a border. I'm not wanting to surround each item in the group by the entire group.</p>
  
  <p>How do I accomplish something like the picture below with a border around the entire group?</p>
  
  <p><img src="https://i.stack.imgur.com/Rnq1j.png" alt="alt text"></p>