Operating system: Windows 7 x64
Graphics card: NVIDIA GeForce GTX 580
Short description of error
With viewport shading Color set to Material or Texture, changing the active Grease Pencil Layer via the Dopesheet doesn't update the viewport with respect to the Fade Layers overlay, so the viewport looks as if the active layer hasn't changed. In other shading Color types, it updates properly as expected.
Exact steps for others to reproduce the error
Create new Grease Pencil object, draw on two layers, set viewport shading color type to Random, enable Fade Layers overlay, change active layer via Dopesheet (layer fade updates as expected), change viewport color type to Material, change active layer via Dopesheet (layer fade doesn't update).