anchor.diff:    (setf (tabbar-prev-display-width *tabbar*) 0))
     
   (defun tabbar-off ()
  -  (when *use-tabbar*
  -    (setf *use-tabbar* nil)
  +  (when (variable-value 'tabbar :global)
       (tabbar-clear-cache)
       (delete-window *tabbar*)
       (setf *tabbar* nil)))
     
   (defun tabbar-on ()
  -  (unless *use-tabbar*
  -    (setf *use-tabbar* t)
  +  (unless (variable-value 'tabbar :global)
       (tabbar-init)))
   
  -(defun enable-tabbar-p ()
  -  *use-tabbar*)
  +(define-editor-variable tabbar t ""
  +  (lambda (value)
  +    (if value
  +        (tabbar-on)
  +        (tabbar-off))))
   
   (define-command toggle-tabbar () ()
  -  (if (enable-tabbar-p)
  -      (tabbar-off)
  -      (tabbar-on)))
  +  (setf (variable-value 'tabbar :global)
  +        (not (variable-value 'tabbar :global))))
   
   (define-key *global-keymap* (list (code-char 550)) 'tabbar-next) ; control + pagedown
   (define-key *global-keymap* (list (code-char 555)) 'tabbar-prev) ; control + pageup
  
positive.code:     (let ((button (button-at p)))
        (when button
          (button-action button)))))
  
negative.code:   (:use :cl :lem :lem.button)
    (:export :tabbar-active-tab-attribute
             :tabbar-attribute
             :tabbar-background-attribute
             :tabbar))
  (in-package :lem.tabbar)
  
  (define-attribute tabbar-active-tab-attribute
  