How can I set a property of a DropShadowEffect via a Trigger in a ControlTemplate?

Question

I have a Button ControlTemplate and I'm trying to modify a DropShadowEffect on a Border by using a Trigger. Here is my Xaml:

<Button.Template>
  <ControlTemplate TargetType="Button">
    <Border x:Name="ButtonBorder" Margin="10" CornerRadius="5" Background="Gray">
      <Border.Effect>
        <DropShadowEffect ShadowDepth="5" x:Name="BorderEffect" />
      </Border.Effect>
      <ContentPresenter HorizontalAlignment="Center" />
    </Border>
    <ControlTemplate.Triggers>
      <Trigger Property="Button.IsMouseOver" Value="True">
        <Setter Property="Background" TargetName="ButtonBorder" Value="LightGray" />
      </Trigger>
      <Trigger Property="Button.IsPressed" Value="True">
        <Setter Property="Margin" TargetName="ButtonBorder" Value="13,13,7,7" />
        <!-- this is where I get the error -->
        <Setter Property="ShadowDepth" TargetName="BorderEffect" Value="2" />
      </Trigger>
    </ControlTemplate.Triggers>
  </ControlTemplate>
</Button.Template>

I get on error stating that the BorderEffect cannot be found.
I have also tried:

<Setter Property="Effect.ShadowDepth" TargetName="ButtonBorder" Value="2" />

But I also get an error telling me that the property ShadowDepth could not be found on the object of type Effect (because it's using the base class instead of DropShadowEffect)

How can I solve this?

Answer 1

You can set the Effect as a whole in the setter.value

 <Setter Property="Margin" TargetName="ButtonBorder" Value="13,13,7,7" />
    <Setter Property="Effect" TargetName="ButtonBorder" >
      <Setter.Value>
         <DropShadowEffect ShadowDepth="2" />
      </Setter.Value>
    </Setter>
  </Trigger>