3.12) The radio-buttons.

type gr_radio =
  { ra_window : gr_window
  ; mutable ra_left : int
  ; mutable ra_top : int
  ; mutable ra_state : bool
  ; mutable ra_name : string
  ; mutable ra_callback : gr_radio -> event -> bool
  }
;;
The radio-buttons are buttons that toggle state each time the user clicks on them.
The type gr_radio is composed of: The functions linked with the gr_radio type are:
gr_draw_radio -> unit
gr_draw_radio Rad draws the radio-button Rad.
gr_radio_managed : gr_radio -> event -> bool
this is the function used by Camlwin to manage the radio- button objects.