the manual says select faces for vertex groups?  i must have read it wrong then... nope, the whole bit on vertex groups talks about vertices, not faces or polygons.  for instance, "Use your mouse to ⇧ ShiftRMB select more vertices that you want in that group." i didn't think it was harassing you to make a minor point, and especially to say "maybe it's different for making figures," but if it's that important to you to be right about every single little thing... well, more power to you.  you must lead an interesting life.