title: AutoCompleteBox not showing Selected Items
body: <p>If I select items through the AutoCompleteBox dropdown, it populates the SelectedItems collection but doesn't update the UI. Nothing shows.</p>
  
  <p>For example, my AutoCompleteBox you can currently select between 1-12. If I select [1,2,3]
  the list will no longer have [1,2,3] but will still have [4-12] to select from and the selected items don't show. </p>
  
  <p>I've set breakpoints to double check and my SelectedItems collection does populate!</p>
  
  <p>I was wondering how do I get the selected items to show. </p>
  
  <p>I think it has to do with the DisplayMemberPath.</p>
  
  <pre><code>&lt;telerik:RadAutoCompleteBox         
      SelectedItems="{Binding MonthsToSkip, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"  
      ItemsSource="{Binding DateAutoCompleteBox, Mode=TwoWay}"/&gt;
  </code></pre>
  
  <p>.cs:</p>
  
  <pre><code>private List&lt;string&gt; _dateAutoCompleteBox;
  public List&lt;string&gt; DateAutoCompleteBox 
  { 
    get { return _dateAutoCompleteBox; } 
    set { _dateAutoCompleteBox = value; OnPropertyChanged("DateAutoCompleteBox"); } 
  }
  
  public List&lt;string&gt; MonthsToSkip { get; set; }
  </code></pre>