The hierarchy view of the Class Browser lists the immediate superclasses and subclasses of the current class. This view can be useful for navigating the class hierarchy if you want to be able to see both superclasses and subclasses at the same time.
Click on the Hierarchy tab to browse classes with the hierarchy view. The hierarchy view shown in Viewing superclass and subclass information in the Class Browser appears.
Figure 8.6 Viewing superclass and subclass information in the Class Browser
The areas available in the hierarchy view are described below.
LispWorks IDE User Guide (Windows version) - 25 Nov 2011