title: Why does data binding break in OneWay mode?
body: <p>Here's a little XAML fragment. You will see</p>
  
  <pre><code>&lt;StackPanel&gt;
       &lt;TextBox x:Name="txtValue"&gt;250&lt;/TextBox&gt;
       &lt;Slider x:Name="slide" 
               Value="{Binding ElementName=txtValue, Path=Text, 
                               Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" 
              Minimum="0" Maximum="500"&gt;&lt;/Slider&gt;
  &lt;/StackPanel&gt;
  </code></pre>
  
  <ol>
  <li>when you change the textbox value, the slider updates</li>
  <li>If you change the slider value explicitly, the previous behavior breaks a.k.a. stops working.</li>
  </ol>
  
  <p>If I remove the <code>Mode=OneWay</code> set directive, (defaults to two-way) everything works perfectly.</p>
  
  <p>Why is this happening?</p>