title: How to get ToolTip binding to work with a ComboBox?
body: <p>Currently I have a ComboBox defined as:</p>
  
  <pre><code>&lt;ComboBox Name="comboItems" ItemsSource="{Binding Path=EnumDataItems}"
              DisplayMemberPath="Description" 
              ToolTip="{Binding Path=ToolTip}" // never displays the value
              SelectedValuePath="Value" SelectedValue="{Binding Path=Value}" /&gt;
  </code></pre>
  
  <p>Everything works except the ToolTip. The property that it should bind to; <code>ToolTip</code> <em>does</em> contain a value. I'm sure of this because when I do the following, I see a result confirming that ToolTip contains a value:</p>
  
  <pre><code>&lt;ComboBox Name="comboItems" ItemsSource="{Binding Path=EnumDataItems}" 
              DisplayMemberPath="ToolTip" // I replaced 'Description' with 'ToolTip'
              ToolTip="{Binding Path=ToolTip}"
              SelectedValuePath="Value" SelectedValue="{Binding Path=Value}"/&gt;
  </code></pre>
  
  <p>Having replaced <code>Description</code> with <code>ToolTip</code> I can see that the value of ToolTip is appearing on the screen. However</p>
  
  <pre><code>ToolTip="{Binding Path=ToolTip}"
  </code></pre>
  
  <p>still doesn't work. If I attempt to display ToolTip as follows:</p>
  
  <pre><code>ToolTip="ToolTip" 
  </code></pre>
  
  <p>it just displays the word 'ToolTip'.</p>
  
  <p>How can I get <code>ToolTip</code> to display a value?</p>