title: Selecting first item in listbox
body: <p>A listbox works as an auto-complete within a richtextbox I am populating it with items from a collection. I need it to auto select first item every time listbox populates. </p>
  
  <p>How do I do this?</p>
  
  <p>Thank you  </p>
  
  <pre><code>foreach (var ks in ksd.FindValues(comparable))
        {
            lb.Items.Add(ks.Value);
        }
  
        if (lb.HasItems)
        {
            lb.Visibility = System.Windows.Visibility.Visible;
            lb.SelectedIndex = 0; //Suggested solution, still doesn't work 
        }
        else
        {
            lb.Visibility = System.Windows.Visibility.Collapsed;
        }
  </code></pre>