anchor.diff:    ((simple-char
       :initarg :simple-char
       :initform nil
  +    :type (or null character)
       :accessor .simple-char
       :documentation "Lisp primitive character type, like #\a.")
   
      (attributes
       :initarg :attributes
       :initform '()
  +    :type (or null cons)
       :accessor .attributes
       :documentation "List of keywords denoting attributes.")
   
      (color-pair
       :initarg :color-pair
  -    :initform '(:white :black)
  +    :initform nil
  +    :type (or null cons)
       :accessor .color-pair
       :documentation "Two element list of keywords denoting a foreground and background color of the char."))
   
  
positive.code:    (scrolling-region
      :initarg       :scrolling-region
      :initform      nil
      :type          cons
      :documentation "When scrolling is enabled, only scroll the window region from line y1 to y2 given as the list (y1 y2).")
  
     ;; IC / INS / Insert / Einfg key
  
negative.code:    (source
      :initarg       :source
      :initform      nil
      :type          (or null cons)
      :documentation "Position (y x) of the area of the parent window, which is mapped to the subwindow. By default it is identical to the position of the subwindow."))
  
    (:documentation  "A sub-window shares the memory and the display with and has to be contained within a parent window."))
  