How do you debug printable CSS?

Question

I use Firebug and IE Developer Toolbar all the time to debug tricky CSS problems. But occasionally, a tricky bug comes up that only appears when you go to print the page.

Answer 1

I use the WebDeveloper plugin and the CSS --> Display CSS by Media Type --> Print to view the CSS as it would when printed. Firebug's inspection utilities work with the CSS as filtered by the plugin.