* This is a callback that will allow us to create the viewer and initialize it.
*/
@Override
public void createPartControl( Composite parent ) {
bookmarksTree = new TreeViewer(parent);
bookmarksProvider = new BookmarksContentProvider();
bookmarksTree.setContentProvider(bookmarksProvider);
getSite().getWorkbenchWindow().getPartService().addPartListener(bookmarksProvider);
labelProvider = new BookmarksLabelProvider();
bookmarksTree.setLabelProvider(labelProvider);
bookmarksTree.setSorter(new ViewerSorter());