fBlock                                        (Assignable)

        Contains an optional code block that, when present, is evaluated each
        time the PushButton object receives or loses input focus.  The code
        block takes no implicit arguments.  Use the PushButton:hasFocus
        variable to determine if the push 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 PushButton class to provide a
        method of indicating when an input focus change event has occurred.
        The name "fBlock" refers to focus block.