title: XAML GridRow doesn't scale automatically when ErrorTemplate is displayed
body: <p>I have a XAML window with a TextBox, and this TextBox has an ErrorTemplate.</p>
  
  <p>The ErrorTemplate is shown below, and as you can see, I have an AdornedElementPlaceholder, followed by a textbox whose Text field is bound to the ErrorContent:</p>
  
  <pre><code>&lt;ControlTemplate x:Key="ValidationErrorTemplateTextBlock" TargetType="{x:Type Control}"&gt;
      &lt;Border BorderBrush="Red" BorderThickness="1"&gt;
          &lt;StackPanel Orientation="Vertical"&gt;
              &lt;AdornedElementPlaceholder Name="AdornedElementPlaceholder" /&gt;
              &lt;TextBlock Text="{Binding ElementName=AdornedElementPlaceholder, Path=AdornedElement.(Validation.Errors)[0].ErrorContent}" 
                      FontSize="10"
                      Background="Red"
                      Foreground="White"
                      Padding="2" /&gt;
          &lt;/StackPanel&gt;
      &lt;/Border&gt;
  &lt;/ControlTemplate&gt;
  
  &lt;TextBox IsEnabled="{Binding SendMessage}"
                      Text="{Binding AutoMessageSubject, ValidatesOnDataErrors=True, UpdateSourceTrigger=PropertyChanged}"
                      Style="{StaticResource StyleBase}"
                      Validation.ErrorTemplate="{StaticResource ValidationErrorTemplateTextBlock}"
                      HorizontalAlignment="Stretch"
                      Grid.Row="3"
                      Grid.Column="1"
                      Grid.ColumnSpan="2" /&gt;
  </code></pre>
  
  <p>This works fine, except for one thing: the TextBox is inside a GridRow, with a Height="Auto". The row scales itself based on the textbox, but when the ErrorTemplate appears, with an extra TextBox on the bottom - the GridRow doesn't scale up to contain the new TextBox, and the new TextBox overlaps the elements below it.</p>
  
  <p>How can I solve this?</p>