anchor.diff:  (define-command listener-next-input () ()
     (multiple-value-bind (str win)
         (next-history (%listener-history))
  -    (let ((start (marker-point (%listener-marker)))
  +    (let ((start (listener-start-point))
             (end (point-max)))
         (delete-region start end)
         (when win (insert-string str))
  
positive.code: (defpackage :lem.listener-mode
    (:use :cl :lem :lem.util)
    (:export :listener-mode
             :*listener-mode-kemap*
             :listener-start
             :listener-reset-prompt
             :listener-return
  
negative.code: (define-command listener-prev-input () ()
    (multiple-value-bind (str win)
        (prev-history (%listener-history))
      (let ((start (listener-start-point))
            (end (point-max)))
        (delete-region start end)
        (when win (insert-string str))
  