Top down debugging
When using common Java debuggers you have just the source code view of the class for tracing control flow.
But you could have more views giving different perspectives of the application to debug. A method call stack for example can be displayed as a list of method names or alternatively as a sequence diagram showing objects in communication.
Every view displays certain details of the application to debug from an appropriate perspective. You can restrict a call stack displayed by a sequence diagram to objects that are of interest to you.
jBixbe offers a couple of views arranged in view levels (system overview level, design level, source code level). The system overview level gives an overview of the entire application to debug. The design level contains sequence diagrams and structure diagrams and you are free to open a lot of them showing different details of the application. At source code level you have a look at the source code of the application.
A view of a lower level can be considered as a refinement of a higher level view. Sequence diagrams display method calls and method returns between objects but you cannot trace single source codes lines there. To do this, choose a method call, open a source code view and see what happens at the source code level when the method is called. So a sequence diagram is on a higher level than a source code view.