Using the Designer

Case 1: The ParentBarItem associated with the PopupMenu is contained within a BarManager. In this case, just drop-down the popup from "Popup Form", right click on an item, and select the "Begin A Group" item in the context menu.

Case 2: The ParentBarItem is not contained within a BarManager. In this case, edit the SeperatorIndices property of the ParentBarItem indicating the Item-indices in the Items list where you want separators to be introduced.

In Code

You can easily group items within a ParentBarItem in code as follows: