In Elastic Windows, an empty window can be created as a ``container''
window by double-clicking on an existing window border. The location
of the new window depends on the location of that border as in the
open operation. Container windows are typically created for the
purpose of grouping related pieces of information and applying window
operations on all of them at once. Once a window group is created,
dragging and dropping objects inside this window puts the windows for
each object into the group (Figure 
). A separate window is
opened for each object as a member of the group, surrounded by the
container window borders. Objects can also be added and removed from
the group at any time. Users can also open container windows within
container windows to build a hierarchy of windows suitable for their
task. When operations are applied on the group window, its effects are
propagated to all lower-level windows in the group recursively.
