To organize graphic objects in a manager
you place them in multiple storage areas called layers.
Each graphic object stored in a layer is
unique to that layer and can be stored only in that layer.
Instances of the IlvManager class handle a set of graphic
objects derived from the Rogue Wave® JViews class called IlvGraphic.. The different graphic objects
stored throughout the manager all share the same coordinate
system. For this reason, a manager is a tool designed to handle
objects placed on different priority levels. “Priority level” here
means that objects stored in a higher screen layer are displayed
in front of objects in lower layers.