code: void initiateTreeItems(FlowPanel page, Label loadingLabel) {
  
          CmsSitemapTreeItem rootItem = getRootItem();
          m_controller.addPropertyUpdateHandler(new CmsStatusIconUpdateHandler());
          m_controller.recomputeProperties();
          rootItem.updateSitePath();
          // check if editable
          if (!m_controller.isEditable()) {
              // notify user
              CmsNotification.get().sendSticky(
                  CmsNotification.Type.WARNING,
                  Messages.get().key(Messages.GUI_NO_EDIT_NOTIFICATION_1, m_controller.getData().getNoEditReason()));
          }
          String openPath = m_controller.getData().getOpenPath();
          if (CmsStringUtil.isNotEmptyOrWhitespaceOnly(openPath)) {
              m_openHandler.setInitializing(true);
              openItemsOnPath(openPath);
              m_openHandler.setInitializing(false);
          }
          page.remove(loadingLabel);
      }
docs: Builds the tree items initially.<p>
  
  @param page the page
  @param loadingLabel the loading label, will be removed when finished