Drag and Drop Expander in WPF

Question

I have a Expander as a ListBoxItem ,

I want to to add support for drag and drop the Expander item with in the Listbox.

I found some nice tutorial from the following location.

http://psiman.wordpress.com/2006/12/07/reordereablelistbox/

i implemented this in my project, but the problem is i am able to drag and drop only when the Expander is Open.

But i want to Drag and drop when the Expander is closed.