fBlock                                       (Assignable)

        Contains an optional code block that, when present, is evaluated each
        time the RadioButto object receives or loses input focus.  The code
        block takes no implicit arguments.  Use the RadioButto:hasFocus
        instance variable to determine if the radio button is receiving or
        losing input focus.  A value of true (.T.) indicates that it is
        receiving input focus; otherwise, a value of false (.F.) indicates
        that it is losing input focus.

        This code block is included in the RadioButto class to provide a
        method of indicating when an input focus change event has occurred.
        The name "fBlock" refers to focus block.