anchor.diff:  (defvar *action-callback* nil)
   (defvar *focus-attribute* nil)
   (defvar *non-focus-attribute* nil)
  +
  +(defclass popup-window (floating-window)
  +  ()
  +  (:default-initargs
  +   :border +border-size+))
   
   (define-attribute popup-menu-attribute
     (t :foreground "white" :background "RoyalBlue"))
  
positive.code:            (lem::window-set-pos dst-window x y)
             dst-window)
            (t
             (make-instance 'floating-window
                            :buffer buffer
                            :x x
                            :y y
                            :width width
                            :height height
                            :use-modeline-p nil)))))
  
negative.code:         (start-timer (* timeout 1000) nil 'clear-popup-message))
        window)))
  
  (defun display-popup-message-default (text timeout)
    (clear-popup-message)
    (multiple-value-bind (buffer width height)
        (make-popup-buffer text)
      (display-popup-buffer-default buffer timeout (list width height))))
  
  (defmethod lem-if:display-popup-message (implementation text timeout)
    (display-popup-message-default text timeout))
  
  (defmethod lem-if:display-popup-buffer (implementation buffer width height timeout)
    (display-popup-buffer-default buffer timeout (list width height)))
  
  (defmethod lem-if:delete-popup-message (implementation popup-message)
    (when (windowp popup-message)
  