The class tracker view itself offers add and
remove buttons in the top right corner as well.
If you profile with JVMTI (Java 1.5 and higher), you can select whether to use the total number of objects in the heap as the value for the graph or only the recorded objects. For JVMPI (Java 1.4 and lower), the recorded objects are always used.
If you track recorded objects, you can select their liveness which is explained in the help for the recorded objects view.