CheckBox
 Create check boxes, which are controls that can be toggled on or off by a
 user
------------------------------------------------------------------------------
 Description

     Check boxes present a choice to the user which can be either on or off.
     When a check box is clicked, its state is toggled (as indicated by an
     X in the box) between checked (on) and unchecked (off).

     The CheckBox class has been designed to be easily integrated into the
     standard CA-Clipper GET/READ system in addition to providing the
     necessary functionality to be utilized on its own.

 Examples

     .  This example creates and integrates a check box within a Get
        List and activates it by performing a READ:

        STORE SPACE (25) TO Name
        STORE .T. TO Married
        STORE SPACE (19) TO Phone

        CLS

        @    5,10 SAY "Customer Name: " GET Name
        @  7,10 SAY "Married?:     " GET Married CHECKBOX
        @  9,10 SAY "Home Phone:    " GET Phone

        READ

        ? ALLTRIM (Name) + " IS " + IIF(Married,"","NOT") + "Married."
        WAIT