Page tiles should be transparent if the body's background has alpha.

(GraphicsLayer
  (anchor 0.00 0.00)
  (bounds 785.00 1024.00)
  (children 1
    (GraphicsLayer
      (bounds 785.00 1024.00)
      (contentsOpaque 1)
      (tile cache coverage 0, 0 785 x 1024)
      (tile size 785 x 512)
      (top left tile 0, 0 tiles grid 1 x 2)
      (in window 1)
    )
  )
)
(GraphicsLayer
  (anchor 0.00 0.00)
  (bounds 785.00 1024.00)
  (children 1
    (GraphicsLayer
      (bounds 785.00 1024.00)
      (backgroundColor #00000033)
      (tile cache coverage 0, 0 785 x 1024)
      (tile size 785 x 512)
      (top left tile 0, 0 tiles grid 1 x 2)
      (in window 1)
    )
  )
)
(GraphicsLayer
  (anchor 0.00 0.00)
  (bounds 785.00 1024.00)
  (children 1
    (GraphicsLayer
      (bounds 785.00 1024.00)
      (contentsOpaque 1)
      (tile cache coverage 0, 0 785 x 1024)
      (tile size 785 x 512)
      (top left tile 0, 0 tiles grid 1 x 2)
      (in window 1)
    )
  )
)
(GraphicsLayer
  (anchor 0.00 0.00)
  (bounds 785.00 1024.00)
  (children 1
    (GraphicsLayer
      (bounds 785.00 1024.00)
      (contentsOpaque 1)
      (backgroundColor #CCCCCC)
      (tile cache coverage 0, 0 785 x 1024)
      (tile size 785 x 512)
      (top left tile 0, 0 tiles grid 1 x 2)
      (in window 1)
    )
  )
)