addObserver(pages);
outlines = new OutlineTree(this);
addObserver(outlines);
form = new FormTree(this);
addObserver(form);
xref = new XRefTable(this);
addObserver(xref);
navigationTabs = new JTabbedPane();
navigationTabs.addTab("Pages", null, new JScrollPane(pages), "Pages");
navigationTabs.addTab("Outlines", null, new JScrollPane(outlines), "Outlines (Bookmarks)");
navigationTabs.addTab("Form", null, new JScrollPane(form), "Interactive Form");