NAME
        OffGadget -- disable the specified gadget.

    SYNOPSIS
        OffGadget( gadget, window, requester )
                   A0      A1      A2

        VOID OffGadget( struct gadget *, struct window *,
                struct requester * );

    FUNCTION
        This command disables the specified gadget.  When a gadget is
        disabled, these things happen:
             - its imagery is displayed ghosted
             - the GFLG_DISABLED flag is set
             - the gadget cannot be selected by User

        The window parameter must point to the window which contains the
        gadget, or which contains the requester that contains the gadget.
        The requester parameter must only be valid if the gadget has the
        GTYP_REQGADGET flag set, a requirement for all requester gadgets.

       NOTE:  it's never safe to tinker with the gadget list yourself.  Don't
       supply some gadget that Intuition hasn't already processed in
       the usual way.

     NOTE: for compatibility reasons, this function will refresh all
        gadgets in a requester, and all gadgets from gadget to the
        end of the gadget list if gadget is in a window.

        If you want to improve on this behavior, you may perform the
        equivalent operation yourself: remove a gadget or gadgets,
        change the state of their GFLG_DISABLED flag, replace the
        gadgets using addglist(), and selectively call refreshglist().

    INPUTS
        gadget = pointer to the gadget that you want disabled
        window = pointer to a window structure containing the gadget or
            containing the requester which contains the gadget
        requester = pointer to a requester (may by null if this isn't
           a requester gadget (i.e. GTYP_REQGADGET is not set)).

    RESULT
        None

    BUGS

    SEE ALSO
        ongadget(), addgadget(), refreshgadgets()