I've implemented that kind of drag&drop into a ZO_SortFilterList (or similar) within LibAddonMenu order list box widget too.
https://www.esoui.com/downloads/info...Boxwidget.html
Using a label at the cursor to show the currently dragged entry but I was also missing some kind of visual "where am I above and where is it inserted between" identifier (if I had not added that by other means, I'm not sure anymore
).