sBlock                                        (Assignable)

        Contains an optional code block that, when present, is evaluated each
        time the PushButton object's state changes.  The code block takes no
        implicit arguments.  Use the PushButton:buffer variable to determine
        if the push button is pressed or released.  A value of true (.T.)
        indicates that it is being pressed; otherwise a value of false (.F.)
        indicates that it is being released.

        This code block is included in the PushButton class to provide a
        method of indicating when a state change event has occurred.  The
        name "sBlock" refers to state block.