/**
  * Add a view listener to this application. The view listener is in fact a ListDataListener, which
  * will be notified with intervalAdded() and intervalRemoved() events when views are added or
  * removed, and with a contentsChanged() event when the current view is changed.
  */
 public void addViewListener(ListDataListener listener) {
   _views.addListDataListener(listener);
 }
 /**
  * Add a document listener to this application. The document listener is in fact a
  * ListDataListener, which will be notified with intervalAdded() and intervalRemoved() events when
  * documents are added or removed, and with a contentsChanged() event when the current document is
  * changed.
  */
 public void addDocumentListener(ListDataListener listener) {
   _documents.addListDataListener(listener);
 }