title: WPF Binding with RelativeSource and AncestorType
body: <p>I have a WPF application. It has a grid that is split into 4 rows. In the 2 row I have a datagrid that has its datacontext set to an object of OrderBlock. This all works fine. However I would like one of the column header text value of the datagrid be bound to a property in my view model.</p>
  
  <p>Below is an example of what I have tried unsuccessfully.</p>
  
  <pre><code>&lt;DataGridTextColumn Header="{Binding RelativeSource={RelativeSource 
     AncestorType={x:Type Window}}, Path=ColumnHeadInfo}" 
     Binding="{Binding RejectReason}" IsReadOnly="True"/&gt;
  </code></pre>