Container controls (for example, a frame or group box) allow you to place other controls on top of them. Place a control on a container control as you would when positioning a control on the form. If you position your control over a control that is not a container in add mode, the cursor changes to the NO cursor. For details about allowing docking in a container control, see "Allowing Control Docking", earlier in this chapter.
A control that is positioned on a container control becomes a child control of the container, or parent, control. The position coordinates of a child control are always relative to its parent control. Child controls remain relative to the parent so that they move if the parent control moves.
To change the parent of a control, perform one of the following actions
Use the Properties dialog.
Drag the child control onto a container control.
When you drag a control, the control under the mouse pointer at the time of the mouse up action is made the parent control, unless the NO cursor is displayed, in which case the drag operation is aborted. The parent control is not changed when the mouse up (or drop) is actioned over a selected control.