title: Binding IsReadOnly using IValueConverter
body: <p>Maybe I'm misunderstanding how to use an IValueConverter or data binding (which is likely), but I am currently trying to set the IsReadOnly property of a DataGridTextColumn depending on the value of a string. Here is the XAML:</p>
  
  <pre><code>&lt;DataGridTextColumn Binding="{Binding Path=GroupDescription}" Header="Name"
                      IsReadOnly="{Binding Current,
                                   Converter={StaticResource currentConverter}}"/&gt;
  </code></pre>
  
  <p>And here is my converter:</p>
  
  <pre><code>public class CurrentConverter : IValueConverter
  {
      public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
      {
          string s = value as string;
          if (s == "Current")
          {
              return false;
          }
          else
          {
              return true;
          }
      }
  
      public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
      {
          throw new NotSupportedException();
      }
  }
  </code></pre>
  
  <p>Currently, the column is always editable, the converter seems to do nothing. Does anyone have some thoughts as to why this is happening?</p>