Possible issue with Canvas and Compositors?

I noticed when I create a Canvas and the target uses compositors, the first frame is rendered without compositors enabled and then they suddenly turn on. I'm not sure if this is a MyGUI-specific issue but I don't recall seeing it - it looks a bit ugly!

Any suggestions where I can look to address this - MyGUI or Ogre, etc - very welcome. I only notice it on iOS but am not sure it is iOS-specific.