i just watch the video, when the keyboard is exposed, the screen blank for a moment why is that? this also happen when the keyboard closed.

N97 also do the same thing, but this is acceptable because it has portrait and landscape orientation however N900 only have landscape orientation so what is that? is the screen refreshing?

one more thing, the panoramic desktop, is there only 4 of them like in the video? or we can add more?