private void setupCentralPanel() {
    myCentralPanel.removeAll();
    if (myUsagePreviewPanel != null) {
      Disposer.dispose(myUsagePreviewPanel);
      myUsagePreviewPanel = null;
    }
    JScrollPane pane = ScrollPaneFactory.createScrollPane(myTree);

    if (UsageViewSettings.getInstance().IS_PREVIEW_USAGES) {
      Splitter splitter =
          new Splitter(false, UsageViewSettings.getInstance().PREVIEW_USAGES_SPLITTER_PROPORTIONS);
      pane.putClientProperty(UIUtil.KEEP_BORDER_SIDES, SideBorder.RIGHT);

      splitter.setFirstComponent(pane);
      myUsagePreviewPanel = new UsagePreviewPanel(myProject);
      myUsagePreviewPanel.setBorder(IdeBorderFactory.createBorder(SideBorder.LEFT));
      Disposer.register(this, myUsagePreviewPanel);
      splitter.setSecondComponent(myUsagePreviewPanel);
      myCentralPanel.add(splitter, BorderLayout.CENTER);
    } else {
      myCentralPanel.add(pane, BorderLayout.CENTER);
    }
    myCentralPanel.add(myButtonPanel, BorderLayout.SOUTH);

    myRootPanel.revalidate();
  }
  @Override
  protected JComponent createCenterPanel() {
    JPanel panel = new JPanel(new BorderLayout());

    // Toolbar

    DefaultActionGroup group = new DefaultActionGroup();

    fillToolbarActions(group);

    group.addSeparator();

    ExpandAllAction expandAllAction = new ExpandAllAction();
    expandAllAction.registerCustomShortcutSet(
        new CustomShortcutSet(
            KeymapManager.getInstance()
                .getActiveKeymap()
                .getShortcuts(IdeActions.ACTION_EXPAND_ALL)),
        myTree);
    group.add(expandAllAction);

    CollapseAllAction collapseAllAction = new CollapseAllAction();
    collapseAllAction.registerCustomShortcutSet(
        new CustomShortcutSet(
            KeymapManager.getInstance()
                .getActiveKeymap()
                .getShortcuts(IdeActions.ACTION_COLLAPSE_ALL)),
        myTree);
    group.add(collapseAllAction);

    panel.add(
        ActionManager.getInstance()
            .createActionToolbar(ActionPlaces.UNKNOWN, group, true)
            .getComponent(),
        BorderLayout.NORTH);

    // Tree
    expandFirst();
    defaultExpandTree();
    installSpeedSearch();

    JScrollPane scrollPane = ScrollPaneFactory.createScrollPane(myTree);
    scrollPane.setPreferredSize(new Dimension(350, 450));
    panel.add(scrollPane, BorderLayout.CENTER);

    return panel;
  }
  public static Pair<JPanel, JBList> createActionGroupPanel(
      ActionGroup action, final JComponent parent, final Runnable backAction) {
    JPanel actionsListPanel = new JPanel(new BorderLayout());
    actionsListPanel.setBackground(getProjectsBackground());
    final JBList list = new JBList(action.getChildren(null));
    list.setBackground(getProjectsBackground());
    list.installCellRenderer(
        new NotNullFunction<AnAction, JComponent>() {
          final JLabel label = new JLabel();

          {
            label.setBorder(JBUI.Borders.empty(3, 7));
          }

          @NotNull
          @Override
          public JComponent fun(AnAction action) {
            label.setText(action.getTemplatePresentation().getText());
            Icon icon = action.getTemplatePresentation().getIcon();
            label.setIcon(icon);
            return label;
          }
        });
    JScrollPane pane = ScrollPaneFactory.createScrollPane(list, true);
    pane.setBackground(getProjectsBackground());
    actionsListPanel.add(pane, BorderLayout.CENTER);
    if (backAction != null) {
      final JLabel back = new JLabel(AllIcons.Actions.Back);
      back.setBorder(JBUI.Borders.empty(3, 7, 10, 7));
      back.setHorizontalAlignment(SwingConstants.LEFT);
      new ClickListener() {
        @Override
        public boolean onClick(@NotNull MouseEvent event, int clickCount) {
          backAction.run();
          return true;
        }
      }.installOn(back);
      actionsListPanel.add(back, BorderLayout.SOUTH);
    }
    final Ref<Component> selected = Ref.create();
    final JPanel main = new JPanel(new BorderLayout());
    main.add(actionsListPanel, BorderLayout.WEST);

    ListSelectionListener selectionListener =
        new ListSelectionListener() {
          @Override
          public void valueChanged(ListSelectionEvent e) {
            if (e.getValueIsAdjusting()) {
              // Update when a change has been finalized.
              // For instance, selecting an element with mouse fires two consecutive
              // ListSelectionEvent events.
              return;
            }
            if (!selected.isNull()) {
              main.remove(selected.get());
            }
            Object value = list.getSelectedValue();
            if (value instanceof AbstractActionWithPanel) {
              JPanel panel = ((AbstractActionWithPanel) value).createPanel();
              panel.setBorder(JBUI.Borders.empty(7, 10));
              selected.set(panel);
              main.add(selected.get());

              for (JButton button : UIUtil.findComponentsOfType(main, JButton.class)) {
                if (button.getClientProperty(DialogWrapper.DEFAULT_ACTION) == Boolean.TRUE) {
                  parent.getRootPane().setDefaultButton(button);
                  break;
                }
              }

              main.revalidate();
              main.repaint();
            }
          }
        };
    list.addListSelectionListener(selectionListener);
    if (backAction != null) {
      new AnAction() {
        @Override
        public void actionPerformed(@NotNull AnActionEvent e) {
          backAction.run();
        }
      }.registerCustomShortcutSet(KeyEvent.VK_ESCAPE, 0, main);
    }
    return Pair.create(main, list);
  }