How to create custom dropdownlist with Grouped data in Adobe Flex?

Question

I wish to create a custom dropdown list which shows grouped data. The one having title of (category) sub-data shouldn't be selectable while other ones (names) should be selectable.

Expected output should be something like below data to be shown in Dropdown list

Administrators
       John
       David
Users
      Peter
      Steven
      James
Members
Jury 

Image for Reference: