Printing of PDF documents being viewed in Firefox is handled by the PDF plugin, not by Firefox, so you'll need to use the "page range" pref in the print dialog for that PDF program if you don't want to print the entire document. AFAIK, Adobe doesn't provide a way of selecting just a part of a page ''(a "selection" from a page as with Firefox on web pages)'' to be printed, but you might want to check that out with Adobe support.