(define-gboxed-variant-cstruct event "GdkEvent"
  (type event-type)
  (window (g:object window))
  (send-event (:boolean :int8))
  (:variant type
            ...
            ((:configure) event-configure
             (x :int)
             (y :int)
             (width :int)
             (height :int))
  ... ))