title: WPF DataGrid Double Click event in CellEditingTemplate
body: <p>I have a WPF DataGrid. With a single click I can edit every cell in the DataGrid.<br>
  I also want to open a new Window on a double click.</p>
  
  <p>That double click event works for a normal DataGridTextColumn like this</p>
  
  <pre><code>&lt;DataGridTextColumn Binding="{Binding Path=Name}" &gt;
      &lt;DataGridTextColumn.EditingElementStyle&gt;
          &lt;Style TargetType="TextBox"&gt;
              &lt;EventSetter Event="MouseDoubleClick" Handler="CellEditDoubleClick"/&gt;
          &lt;/Style&gt;
      &lt;/DataGridTextColumn.EditingElementStyle&gt;
  &lt;/DataGridTextColumn&gt;
  </code></pre>
  
  <p>But how to do it using a Template like this when I am in editing mode of the TextBox:</p>
  
  <pre><code>&lt;DataGridTemplateColumn Header="Weight"&gt;
      &lt;DataGridTemplateColumn.CellTemplate&gt;
          &lt;DataTemplate&gt;
              &lt;TextBlock Text="{Binding Path=Weight}" /&gt;
          &lt;/DataTemplate&gt;
      &lt;/DataGridTemplateColumn.CellTemplate&gt;
      &lt;DataGridTemplateColumn.CellEditingTemplate&gt;
          &lt;DataTemplate&gt;
              &lt;TextBox x:Name="WeightEditTextBox" Text="{Binding Path=Weight}" &gt;
                  &lt;i:Interaction.Behaviors&gt;                       
                      &lt;helper:TextBoxInputRegExBehaviour RegularExpression="^\d+\,?\d*$" /&gt;
                  &lt;/i:Interaction.Behaviors&gt;
              &lt;/TextBox&gt;
          &lt;/DataTemplate&gt;
      &lt;/DataGridTemplateColumn.CellEditingTemplate&gt;
  &lt;/DataGridTemplateColumn&gt;
  </code></pre>
  
  <p>Currently when in edit mode the double click does get fired.<br>
  Perfect would be a solution that works for the complete DataGrid which I do not have to add to every single column in the DataGrid.</p>