Child Panels
You can configure LoadPanel so that panels appear within other panels in your user interface. When you do this, the principal panel is called the parent panel; panels within it are child panels. Child panels can appear within other child panels too.
A child panel helps developers control the appearance of the user interface. Users cannot drag a child panel outside its parent panel. And if users shrink a parent panel, a child panel might be partially or completely hidden in the shrunken panel view.