How to handle Validations on Custom Control

Question

I recently wrote my first custom control, an autocomplete textbox. Its Controltemplate consists of something like this

<Grid >
  <Border/>
  <TextBlock x:Name="Label"/>
  <TextBox x:Name="TextLabel"/>
</Grid>

The first Textblock is used as a Label, the second one shows the content. The TextLabel binds on an Object, let's call it Customer If the underlying search doesn't find a Customer object, I want to show the errortemplate. When defining the TextLabel like this

<TextBox x:Name="PART_Editor"
    HorizontalAlignment="Stretch"
    VerticalAlignment="Center"
    Validation.ErrorTemplate="{DynamicResource ValidationErrorTemplate}"
    Style="{StaticResource TransparentTextBoxStyle}"
    Text="{Binding Path=Text, RelativeSource={RelativeSource Mode=TemplatedParent}, 
           Mode=TwoWay, ValidatesOnNotifyDataErrors=True, 
           NotifyOnValidationError=True, 
           ValidatesOnDataErrors=True, 
           UpdateSourceTrigger=PropertyChanged}" >                                                                                
</TextBox>

the Validation is made and the error template of the textbox is shown. Unfortunately the Red Border is only around the inner TextBox and not around the whole custom control which looks just not good.

I was wondering how to achieve two things:

• How can the ErrorTemplate of the CustomControl be triggered when one of the child-validations fail?
• Do I have to specify all these NotifyOnValidationerror properties or is it possible to catch all errors on entity level and show the same ErrorTemplate

If you need additional Information, please just ask