public void showSubDiagram(GraphID id) {
    sequenceDiagram.addSubDiagram(id, lineMap.get(id), arrowMap.get(id));
  }
Create the GUI and show it. For thread safety, this method should be invoked from the
event-dispatching thread.
geode-core/src/test/java/org/apache/geode/sequence/GemfireSequenceDisplay.java