The FAA regs online:
http://www.faa.gov/avr/AFS/FARS/far-125.txt
I could not find anything about window shades in FAR Part 125 which I think is the applicable area, except for regs on window shades during simulated nighttime emergency testing.
edited to delete reference to seatbacks as off topic.
[This message has been edited by Warrenlm (edited 05-22-2001).]