Dragging and dropping selected items in this empty window will open as many windows as the cardinality of the selection all grouped inside the empty window. Figure 4 shows the result of creating a window group for visualizing all new incoming mails from a person.
Users can add more windows into a group later as well.
A window can be removed from a group by simply closing that window. Hierarchies of windows can be created similarly by opening an empty window inside another empty window.