private void buildMenu() {
    menuContainer.getChildren().clear();
    for (MenuItem item : getSkinnable().getItems()) {
      if (item instanceof Menu) {
        // item is a submenu
        menuContainer.getChildren().add(buildSubmenu(item));
      } else {
        // item is a regular menu item
        menuContainer.getChildren().add(buildMenuItem(item));
      }
    }
  }
Defines the layout of all parts in the skin.
workbenchfx-core/src/main/java/com/dlsc/workbenchfx/view/controls/NavigationDrawerSkin.java