title: WPF Window Background ImageBrush not tiling
body: <p>I have a window with a background image.  The image may change at runtime which really should not matter for this.</p>
  
  <p>I want the image to be fixed to the top left (which it is) and not scale (which is also correct.  But I need the image to repeat (tile) when the window is made larger than the image.  I am doing ...</p>
  
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  <p>What am i missing?</p>
  
  <p>TIA</p>