Help looking for a ComboBox Treeview

Does anyboy know where I can get a ComboBox control that can contain a Treeview as the drop down selection, I found a project on CodeProject, but it doesn't really suit our needs. I have searched extensively using Google with no luck.

The project on CodeProject if anyone is interested is here: http://www.codeproject.com/useritems/dropdowntree.asp

Thanks.