Scroll Bars

  You can use the vertical and horizontal   scroll bars  to display
  information outside the borders of a window.  A scroll bar has
  stepper arrows     at each end of a scroll region and a  slider
  within the scroll region.

  In the Library and Navigation windows, you can also use
  outer stepper arrows to display information.

  Additional topics:

  *   Using Menus, Controls, and Dialog Boxes

  *   Bookreader Help Topics