Hi Belarus,
A DropDownBarItem is a BarItem that gets drawn with an arrow button to its right, which when clicked, will pop up a window (note: not a menu) represented by a PopupControlContainer. So it is not possible to have another BarItems in DropDownBarItem.
Please refer the Online documentation for more details:
http://www2.syncfusion.com/ug_61/toolswin/default.htmlUnder Tools.Windows
Overview-->Controls-->Menus package---->Concepts and Features----->XP Menu Bars--->Bar Items-->Types of BarItems-->DropDownBarItem
Kindly let us know if you need any further assistance.
Best Regards,
Jeba.