Auto-rolling rear / back window?

I've had the window out a few times in the Avalanche and it certainly makes for
improved air flow (although, the sun-roof + rear windows is a great option too).  I
recently saw a Toyota Tundra with a rolling rear / back window and thought that would
be an awesome upgrade on my Avalanche.  However, I wasn't sure if that was even
feasible with the Avalanche's mid-gate.  Or, if it's cost prohibitive given the mid-gate
and size of the window.  Certainly wouldn't add anything other than aesthetics and
being able to control the window from the dash.

Thanks,

- Greg  

(although, depending on what the home HVAC Repair guy says, any non-critical
updates will be put on ice).