  (define-class tab-group% item% () #f
    button-focus
    set
    set-label
    delete
    append
    enable
    set-selection
    number
    get-selection
    on-drop-file
    pre-on-event
    pre-on-char
    on-size
    on-set-focus
    on-kill-focus)
  (define-class group-box% item% () #f
    on-drop-file
    pre-on-event
    pre-on-char
    on-size
    on-set-focus
    on-kill-focus)
