Allow primary page to rotate instead of bouncing at the edge.

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The main two pages bounce at their left (or right) edge.
I should find it convenient if they would rotate regardless of shifting the 
page to the right or to the left.

I find myself unable to remember whether I have to shift the current page left 
or right,so I end up with a 50% winning chance to shift to the corect direction.

I encountered the loop through behaviour with the primary nav pages on the ICS 
menu and I liked it very much...

Original issue reported on code.google.com by tf5...@gmail.com on 21 Jul 2012 at 11:21