Unresponsive/blank CocosSharpView when returning from sleep on Android

[Meekohi]

Only tested on Android. Everything works fine if the app is put into the background and reopened, but if you hit the power button and put the phone to sleep, when you come back the cocossharp screen is unresponsive (or blank if something else covers it then is removed). Creating a new CocosSharpView from scratch works, but isn't ideal.