private static Menu MainMenu;

MainMenu = new Menu("Root Menu", "rmenu", true) // true is root menu

var Barrier = new Menu("Barrier", "mbarrier");
Barrier.AddItem(new MenuItem("useBarrier", "Enable Barrier")).SetValue(true);
Barrier.AddItem(new MenuItem("useBarrierPct", "Barrior on min HP % ")).SetValue(new Slider(35, 1));
Barrier.AddItem(new MenuItem("useBarrierDmg", "Barrier on damage %")).SetValue(new Slider(40, 1));

var BarrierSub = new Menu("Barrier Submenu", "msubmenu");
Barrier.AddItem(new Menu("enableBarrier", "Use Barrier ?")).SetValue(true);

Barrier.AddSubMenu(BarrierSub);
MainMenu.AddSubMenu(Barrier);

MainMenu.AddToMainMenu();