title: Wpf grouped combobox with an expander
body: <p>I was able to find an example of a grouped combobox here <a href="http://www.jarloo.com/wpf-combobox-with-groupings/" rel="nofollow">http://www.jarloo.com/wpf-combobox-with-groupings/</a></p>
  
  <p>Its perfect for my use except I need an additional behavior. The items should all be collapsible under their respective headers (Using expanders). </p>
  
  <p>For eg.
  Fruit
   Apple
   Orange
   Grape
  Animals
   Cat
   Dog
   Cow</p>
  
  <p>The above items will be displayed in a combobox in a grouped style but I will like each headers (Here it would be Fruit, Animals) to be collapsible using an expander. Could you please help with an example?</p>
  
  <p>Thanks,
  Chev</p>