title: Numeric textEdit default value to empty
body: <p>I use the editor <code>TextEdit</code> with a numeric mask type and I set the <code>Mask="n"</code> and <code>AllowNullInput="True"</code>, I want that when <code>TextEdit</code> contains the value <code>0</code> it displays empty, but it is not working.</p>
  
  <p>This is my code:</p>
  
  <pre><code>&lt;dxe:TextEdit Width="158"
                Text="{Binding Debut, Mode=TwoWay,  UpdateSourceTrigger=PropertyChanged}"
                HorizontalContentAlignment="Right"
                Mask="n"
                AllowNullInput="True"
                IsEnabled="{Binding B_debut}"
                KeyboardNavigation.TabIndex="0"&gt;
  </code></pre>