title: Determine the bounding rect of a WPF element relative to some parent
body: <p>I consider this a pretty simple request, but I can't seem to find a conclusive answer in my searches. How can I determine the bounds of a particular visual element in my window, relative to some other parent element?</p>
  
  <p>I've tried using <code>LayoutInformation.GetLayoutSlot</code> but this just seems to return a <code>Rect</code> at 0,0 and doesn't reflect the actual location of the element.</p>
  
  <p>What I'm trying to do is take a "screenshot" of a window using <code>RenderTargetBitmap</code> and then crop it to a particular element, but I can't get the element's bounds to know what to crop the bitmap to!</p>