Last Selection State of Dropdown Node using WPF (Explicit Node)

hello all, just wondering if you guys have any methods or functions that can help to retain the previous selection of item in a dropdown menu of an explicit node. I had created a functioning explicit node but every time i close and reopen the graph, the selection done previously will be reset to the first item. So was wondering if you guys have any solution to it.

To give you guys better understanding of what i am explaining, here a short clip of it:

Appreciate your help guys~