Smart Key - Smart Scrolling

When pressed at the end of a line but not the end of a buffer:
  ACTION KEY
     Calls the function given by action-key-eol-function whose
     default value is smart-scroll-up.  This scrolls up according
     to the value of smart-scroll-proportional.  If
     smart-scroll-proportional is nil or if point is on the top
     window line, it scrolls up (forward) a windowful.  Otherwise, it tries
     to bring the current line to the top of the window, leaving point at
     the end of the line and returning t if scrolled, nil if not.  To disable
     this behavior entirely, evaluate this line:
     (customize-set-variable 'action-key-eol-function #'ignore)

  ASSIST KEY
     Calls the function given by assist-key-eol-function whose
     default value is smart-scroll-down.  This scrolls down according
     to the value of smart-scroll-proportional.  If
     smart-scroll-proportional is nil or if point is on the bottom
     window line, it scrolls down (backward) a windowful.  Otherwise, it tries
     to bring the current line to the bottom of the window, leaving point at
     the end of the line and returning t if scrolled, nil if not.  To disable
     this behavior entirely, evaluate this line:
     (customize-set-variable 'assist-key-eol-function #'ignore)