Control option controls the top shade, control command controls bottom shade.

Peter B. wrote:Control option controls the top shade

The help has been corrected. Thanks!

control command controls bottom shade.

Control+arrow moves the bottom shade. The command key is ignored.

James Bucanek wrote:
Control+arrow moves the bottom shade. The command key is ignored.

Control+arrow was usurped by Mission Control and Application windows on my system. Holding control command allowed me to control the bottom shade. I wonder why.