I am trying to create a custom style panel (StyledStackPanel) which is identical to regular StackPanel, that has a custom style. For example - if the style is simply to add an underline, by writing:

<StyledStackPanel>
    <!--User content goes here-->
</StyledStackPanel>

I would like to receive the same appearance as if I wrote:

<StackPanel>
    <!--User content goes here-->
</StackPanel>
<Border Height="1" BorderBrush="Blue"/>

If StackPanel was a Control, I could have replace the DataTemplate of that control. However, it inherits Panel which inherits FrameworkElement.
Is there a way to change the template of a StackPanel?

c# wpf
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