Ok, I managed to use the file drop on my treeview (UltraWinTree) using a inherited custom object - following exactly the Outlook demo you provided.
It works fine for dropping files, either from Explorer or from Outlook. But, as I wrote in my previous post, I still need a way to add this capability to any control, without having to derived it first. Anyway.
The problem, now, is that the tree do not get any other drag/drop event. I found no way to actually have intra-nodes drag & drop - the events are not triggered at all. Did I miss something?
Is it possible for your FileDropTargetManager to filter out files and to forward as a standard operation other types of drag&drop?