title: WPF TreeView ObservableCollection notifying sample code
body: <p>I'm trying to write a C# WPF application and I'm stuck with the TreeView and ObservableCollection.</p>
  
  <p>This is my TreeView Items. </p>
  
  <pre><code>| Root
  --- SubItem
  ------ SubItem
  | Root
  --- SubItem
  ------ SubItem
  ---------- SubItem
  </code></pre>
  
  <p>I'm modifyng this items from other window and I need to update this treeview without re-loading all items. I've made my search and I found ObservableCollection. But I can't understand how to use ObservableCollection and notify changes and update this list.
  Can you give me some sample code or help me with doing that?</p>