Bind the selectedValueProperty of this toggle group to the given property. Passing in a writeable value will result in a bidirectional binding, while passing in a read only value will result in a unidirectional binding.
Generates a writable property that represents the selected value for this toggele group. If the toggles are configured with a value (@see #togglebutton and #radiogroup) the corresponding toggle will be selected when this value is changed. Likewise, if the toggle is changed by clicking it, the value for the toggle will be written to this property.