Setting Panel.Background on a Border object?

Question

I am not understanding how this Button Template Example from Microsoft is working... In its storyboards for its various states, it is setting Panel.Background for a target type

Answer 1

That is because dependency properties can be reused, the Border just adds the property of the Panel via AddOwner. The property field is initialized like this:

public static readonly DependencyProperty BackgroundProperty =
         Panel.BackgroundProperty.AddOwner(typeof(Border), ...

So the Panel.Background property is the same as the Border.Background property.