anchor.diff:                                (style-use-border style))
                 :background-color (if background-color-p
                                       background-color
  -                                    (style-background-color style))))
  +                                    (style-background-color style))
  +              :offset-x (style-offset-x style)
  +              :offset-y (style-offset-y style)))
   
   (defun ensure-style (style)
     (cond ((null style)
  
positive.code:   (let* ((style (ensure-style style))
           (border-size (if (style-use-border style) +border-size+ 0))
           (gravity (ensure-gravity (style-gravity style))))
      (destructuring-bind (x y w h)
          (compute-popup-window-rectangle gravity
                                          :source-window source-window
  
negative.code: (defstruct style
    (gravity :cursor)
    (use-border t)
    (background-color nil)
    (offset-x 0)
    (offset-y 0))
  
  (defun merge-style (style &key (gravity nil gravity-p)
                                 (use-border nil use-border-p)
  