anchor.diff:  (defclass prompt-window-parameters ()
     ((completion-function
       :initarg :completion-function
  -    :reader completion-function)
  +    :reader prompt-window-completion-function)
      (existing-test-function
       :initarg :existing-test-function
  -    :reader existing-test-function)
  +    :reader completion-window-existing-test-function)
      (called-window
       :initarg :called-window
  -    :reader called-window)))
  +    :reader prompt-window-called-window)
  +   (history
  +    :initarg :history
  +    :reader prompt-window-history)))
   
   (defclass prompt-window (floating-window prompt-window-parameters)
     ((start-point
  
positive.code:                          existing-test-function
                           history-name
                           &optional syntax-table)
    (declare (ignore history-name syntax-table))
    (when (lem::frame-prompt-window (current-frame))
      (editor-error "recursive use of prompt window"))
    (let* ((called-window (current-window))
  
negative.code: (defun delete-prompt (prompt-window)
    (let ((frame (lem::get-frame-of-window prompt-window)))
      (when (eq prompt-window (frame-current-window frame))
        (let ((window (prompt-window-called-window prompt-window)))
          (setf (frame-current-window frame)
                (if (deleted-window-p window)
                    (first (window-list))
  