public static ToolStripMenuItem BindCommand(this ToolStripDropDown dropDown, CommandManager commandManager, string commandId, object argument)
        {
            Lifetime<ICommand> command = commandManager.FindCommand(commandId);
            if (command == null)
                throw new ArgumentException();

            return dropDown.BindCommand(command, argument);
        }
        public static ToolStripSeparator BindSeparator(this ToolStripDropDown dropDown, CommandManager commandManager, string commandId)
        {
            Lifetime<ICommand> command = commandManager.FindCommand(commandId);
            if (command == null)
                throw new ArgumentException();

            ToolStripSeparator item = dropDown.AddSeparator();
            item.Tag = new ToolStripItemCommandBinding(dropDown, item, command, (object)null);

            return item;
        }