How to do this flip effect?

I am trying to create the flip navigation effect on flashloaded but not able to work it out so far.

Initially I thought that the movieclip ie being tweened in width and the content is being changed along the way but thats not how it seems to be happening. The far side of the panel becomes smaller in size(which I am not able to do with the simple width/height tween) and the transition is much more smooth.

Can someone help me out with this please.

Thanks a lot.

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