title: Bind TextBox.Text in Watermark attached property to localize it
body: <p>I need to add Watermarks to my WPF application and I am using <a href="https://stackoverflow.com/a/836463/383129">this watermark service</a> to achieve it.</p>
  
  <p>It works just as expected, but I need to localize the text showed as watermark and I can't find a way to achieve it.</p>
  
  <p>My xaml declaration:</p>
  
  <pre><code>&lt;TextBox
      Text="{Binding Name, Mode=TwoWay}"&gt;
      &lt;Watermark:WatermarkService.Watermark&gt;
          &lt;TextBlock
              Text="{Binding &lt;What-goes-here?&gt;}"
          /&gt;
      &lt;/Watermark:WatermarkService.Watermark&gt;
  &lt;/TextBox&gt;
  </code></pre>
  
  <p>My ViewModel:</p>
  
  <pre><code>public class PersonViewModel
  {
      public string Name {get;set;}
  
      public string NameWatermark {get;set;}
  }
  </code></pre>
  
  <p>Thw following lines do NOT work:</p>
  
  <pre><code>Text="{Binding NameWatermark}"
  
  &lt;Window x:Name="ThisWindow"
  ...
  Text="{Binding Path=NameWatermark,
                 ElementName=ThisWindow}"
  </code></pre>
  
  <p>Is there any way to achieve it?</p>
  
  <p>Any help would be appreciated, thanks.</p>