WidgetMDIChild

From SmartWin Wiki

A WidgetMDIChild is a small container which itself can be placed in another container Widget. A good example of a WidgetMDIChild is one tab in the FireFox Web browser which would resemble a WidgetMDIChild. It is closely related to the WidgetMDIParent since it can only be contained within a WidgetMDIParent Widget.