As there have been no replies to his question am I correct in assuming that there isn't a solution available for APEX 5 outside of the FOEX plugin? I had a quick look at jqTREE which looks promising but I could't find any documentation on integrating it with APEX e.g. how to load the tree from SQL (via ajax) and to pass the selected node value in an APEX URL.
The APEX Tree Region cannot do drag and drop. The underlying treeView widget can do drag and drop edit nodes, add/remove nodes and much more. You can see it in action when you use Page Designer. However no one, as far as I know has created a plug-in or any other sample that takes advantage of these things.
You may want to dig into this recent tweet from Niels de Bruijn: