anchor.diff:    width
     modified-p)
   
  -(define-interface make-screen (x y width height use-modeline-p)
  +(define-implementation make-screen (x y width height use-modeline-p)
     (when use-modeline-p
       (decf height))
     (%make-screen :%scrwin (charms/ll:newwin height width y x)
  
positive.code: 
  (defvar *display-background-mode* nil)
  
  (define-interface display-background-mode ()
    (or *display-background-mode*
        (lem.term:background-mode)))
  
  (define-interface set-display-background-mode (mode)
    (check-type mode (or (eql :light) (eql :dark) null))
    (setf *display-background-mode* mode))
  
  (define-interface set-foreground (name)
    (or (term-set-foreground name)
        (error "Undefined color: ~A" name)))
  
  (define-interface set-background (name)
    (or (term-set-background name)
        (error "Undefined color: ~A" name)))
  
  
negative.code:                    (setf x (char-width char x)))))
    (charms/ll:wattroff scrwin attr))
  
  (define-implementation screen-print-string (screen x y string attribute)
    (scrwin-print-string (screen-%scrwin screen) x y string attribute))
  
  (define-implementation screen-move-cursor (screen x y)
    (charms/ll:wmove (screen-%scrwin screen) y x))
  
  