A group box is a rectangle that surrounds a set of controls, such as check boxes or radio buttons, with application-defined text (label) in its upper left corner. The sole purpose of a group box is to organize controls related by a common purpose (usually indicated by the label). The group box has only one style, defined by the constant BS_GROUPBOX. Because a group box cannot be selected, it has no check state, focus state, or push state. An application cannot send messages to a group box.