The best way to understand this is to look at this fiddle.
Notice how mouse wheel over the fixed content in the red box does nothing. I would like the
A much, MUCH simpler, but much less widely supported, answer is the following:
#fixed{ pointer-events:none; }
jsFiddle
Doesn't work in IE at all though unfortunately! But you could use modernizr or somesuch to detect whether it was supported and use the jQuery as a stop-gap where it isn't.
Courtesy of Mr. Dominic Stubbs