On Linux (Fedora 11)
Chrome 4: Doesn't appear to use Alternate - but does print from screen perfectly.
Opera 10: appears to do the same as Chrome, but also fills the last page with the dark background colour.
Konqueror 4.3.3: tried to print visible but didn't print the whole doc (missed that last 1/5th or so) and omitted all images and the header.
arora 0.10.2: basically same as Chrome, some more background colour / images
I'm only printing to PDF for these tests.
On Linux (Fedora 11)
Chrome 4: Doesn't appear to use Alternate - but does print from screen perfectly.
Opera 10: appears to do the same as Chrome, but also fills the last page with the dark background colour.
Konqueror 4.3.3: tried to print visible but didn't print the whole doc (missed that last 1/5th or so) and omitted all images and the header.
arora 0.10.2: basically same as Chrome, some more background colour / images
I can test on Mac when I get home from work.