Navigation Window Topic Arrows
  Some sections in the Navigation window are preceded by
  arrows:
      
       A right arrow indicates that the entry contains suben-
       tries that do not appear on the screen.  Double click on
       the arrow to view the subentries.
      
       A down arrow indicates that the subentries appear on
       the screen.  Double click on the arrow to collapse the
       subentries.
  Additional topics:
  *   Navigation Window Menus
  *   Using Menus, Controls, and Dialog Boxes
  *   Bookreader Help Topics