When I preview a normal edit, I can scroll down to the bottom of the page (below the edit box and submit controls) to check that I typed the category names correctly. The categories for the page-to-be sit down there, hopefully blue and not red.
However, when I preview a formedit, I don't see any categories for the page at all... I guess this is related to the weird category box CSS that makes it appear at the bottom of the page.
On the off-chance that you're an expert, how can I create divs that float like the category box?