anchor.diff:     (select-function
       :initarg :select-function
       :initform nil
  -    :reader menu-item-select-function)))
  +    :reader menu-item-select-function)
  +   (plist
  +    :initarg :plist
  +    :initform nil
  +    :reader menu-item-plist)))
   
   (defun append-menu (menu item)
     (setf (menu-items menu)
  
positive.code:                     :do
                      (insert-string p string :attribute attribute)
                      (move-to-column p column t))
                (put-text-property start p 'function (menu-item-select-function item))))
            (move-to-line (buffer-point buffer) 2))))))
  
  (defun menu-select-1 (set-buffer-fn)
    (alexandria:when-let ((fn (text-property-at (current-point) 'function)))
  
negative.code: (defpackage :lem.menu-mode
    (:use :cl :lem)
    (:export :menu-mode
             :menu
             :menu-item
             :append-menu
             :append-menu-item
             :display-menu
             :menu-property-at))
  (in-package :lem.menu-mode)
  
  (define-attribute head-line-attribute
  