title: Copy a binding from one textbox to another
body: <p>Hopefully a simple starter question from a newbie...</p>
  
  <p>I have a TextBox whose Text property is bound to a ViewModel and DependencyProperty.</p>
  
  <p>When I click on the TextBox I want a second TextBox (an 'Editor' TextBox) to be assigned the same binding as the first. The outcome being that editing the second 'Editor' TextBox will update the first. </p>
  
  <p>Ultimately I want to be able to click any TextBox and edit it in the same 'Editor' TextBox. </p>
  
  <hr>
  
  <p>My Solution using Option 2... Thanks!!:</p>
  
  <pre><code>    private void m_sourceTextBox_MouseDoubleClick(object sender, MouseButtonEventArgs e)
      {
          TextBox sourceTextBox = sender as TextBox;
          if (null != sourceTextBox)
          {
              BindingExpression sourceBindExpression = sourceTextBox.GetBindingExpression(TextBox.TextProperty);
  
              if (sourceBindExpression != null &amp;&amp; sourceBindExpression.ParentBinding != null &amp;&amp; sourceBindExpression.ParentBinding.Path != null)
                  m_editorTextBox.SetBinding(TextBox.TextProperty, sourceBindExpression.ParentBinding);
          }
      }
  </code></pre>