anchor.diff:     (source
       :initarg       :source
       :initform      nil
  -    :type          cons
  +    :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."))
  
positive.code:    (input-blocking
      :initarg       :input-blocking
      :initform      t
      :documentation "Input mode: blocking (t), non-blocking (nil) or blocking duration in (positive integer) miliseconds.")
  
     (enable-fkeys
  
negative.code:    (width
      :initarg       :width
      :initform      0
      :type          integer
      :documentation "The width (second, horizontal, x dimension) of the window.")
  
     (height
      :initarg       :height
      :initform      0
      :type          integer
      :documentation "The height (first, vertical, y dimension) of the window.")
  
     ;; has to be a 2el-list so we can use 1 arg with setf.
  