title: wpf: custom window drop shadow
body: <p>I'm working on a c# wpf app with a custom window (allowtransparency = true, resize = none, window style = none).</p>
  
  <p>Now I would like to add drop shadow similar to the zune pc software. I read up on this and  the included dropshadoweffect is not covering all angles of my window and it is said to kill performance.</p>
  
  <p>I want to implement it like this: I add a margin to my layout grid which I programmatically remove when maximizing the app.</p>
  
  <p>What is the best way to add a drop shadow which can be applied to a grid, which doesn't kill performance and drops shadow in all directions?</p>