As a subclass of a manager, a grapher (instance of
IlvGrapher) inherits all the behavior of managers, including
nesting.
A grapher can be nested in another grapher or in a manager.
It can be collapsed or expanded, and a frame can be set on it.
In addition to having the features inherited from the
IlvManager class, nested graphers allow you to create applications
that define graphs containing subgraphs, with links crossing the graph
boundaries (intergraph links).