A group box is a rectangular area within a dialog box in which you can group together controls that are semantically related. The controls are grouped by drawing a rectangular border around them. Any text associated with the group box is displayed in its upper-left corner. The sole purpose of a group box is to organize controls related by a common purpose, which is 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.
Group box
Because group boxes are opaque in Windows CE, you must always add them to your dialog box template after you have added everything else. Anything you add to the template after you add the group box will be hidden underneath it. By adding group boxes last, you ensure that the group boxes are at the bottom of the Z order and will not hide your other controls.
You create a group box by specifying the BS_GROUPBOX style in the CreateWindow or CreateWindowEx function.