final FileModel fileModel = new FileModel();
panel = new TreePanel(fileModel);
final FlashTree tree = panel.getTree();
tree.addTreeSelectionListener(internalTreeSelectionListener);
tree.addMouseListener(internalTreeClickListener);
add(panel, BorderLayout.WEST);
// Add Drag & Drop capabilities to the panel to make it easier to open files.
new FileDrop(panel, new FileDrop.Listener() {