Fix opaque navbar 2

Second attempt to fix issue #405
Hm. It definitely feels hacky. The problem is, `UIPeriphalHostView` is private API so we shouldn't rely on this.

On rotation, we should receive `UIKeyboardDidChangeFrameNotification`. Can't we utilize that to get the correct frame?

Oh, and I just re-read the comment:

>Here we translate it back to UIWindow coordinates

The problem is, there is no coordinate translation happening on this line.