Simple watermark effect

I'm trying to create a simple watermark effect in my interface using XAML and replicate an effect I used to do in WinForms.

The effect is a large 256x256px graphics file that remains anchored to the bottom right corner of the container (with some margin and transparency). I do know there are such things as the ImageBrush to work with pre-set bitmaps, but I need something which won't make the file go beyond its original size when the window is resized. The object I'm applying it to is already hosting functional controls and I'd like to avoid having to somehow layer a canvas in somewhere and mess up the automatic grid's I'm using for everything else.

[675 byte] By [Nidonocu] at [2007-12-28]