Tree (DefaultTreeModel model) { Tree tree = new Tree(model); tree.setShowsRootHandles(true); tree.setRootVisible(false); tree.setCellRenderer(new PreviewTreeRenderer()); @NonNls String treeName = "ExtractMethodPreview"; tree.setName(treeName); tree.getSelectionModel().addTreeSelectionListener( e -> ApplicationManager.getApplication().invokeLater( () -> onSelectionUpdate())); SmartExpander.installOn(tree); TreeUtil.installActions(tree); TreeUtil.expand(tree, 2); TreeUtil.promiseSelectFirst(tree); PopupHandler.installPopupMenu(tree, IdeActions.EXTRACT_METHOD_TOOL_WINDOW_TREE_POPUP, "ExtractMethodTreePopup"); return tree; }