anchor.diff:  (defcstruct x-client-message-event
     (type :int)
     (serial :unsigned-long)
  -  (send-event bool)
  +  (send-event :boolean)
     (display-ptr :pointer)
     (win window)
     (message-type x-atom)
  
positive.code: (defcstruct x-visibility-event
    (type :int)
    (serial :unsigned-long)
    (send-event bool)
    (display-ptr :pointer)
    (window window)
    (state visibility-state))
  
negative.code: (defcstruct x-button-event
    (type :int)
    (serial :unsigned-long)
    (send-event :boolean)
    (display-ptr :pointer)
    (win window)
    (root window)
  