kindle "show display options" menu is disabled

i am trying out kindle for pc and am reading a textbook.  i found reading to be rather difficult on kindle for pc because of it's jagged scrolling (please complain here).  while looking to add a smooth scrolling option i noticed the view / show display options menu was disabled.

problem: not all books support changing settings like font size and background color.  for example, my textbook has pictures and stuff written in the margins of pages.  if i changed the "words per line" setting, the words would overlap on the pictures or problems would arise from trying to apply features that aren't defined for a textbook.

there is no easy solution.  author's of textbooks need to make books in a e-reading friendly format, which they will have little incentive to do until physical books phase out and e-books really start to catch on.

if you want to know what the dialog box looks like, this is what you're missing out on: