How to set bitmap frame in WPF?

Question

WPF

</TextBox>
        <Border BorderThickness="8">
            <Border.BorderBrush>
                <ImageBrush ImageSource="Images/border.png"/>
            </Border.BorderBrush>
        </Border>

I'm trying to put a raster frame in this way. As long as the proportions are not distorted, everything works, but when stretched, the picture moves.
Is there no way to apply a border like in CSS?