Drag 'n' drop treeview

Hi !
I try to add drag'n'drop function in the async treeview plugin by Jörn
Zaefferer
And i have a problem !
Maybe it's a bug in the drag 'n' drop function, but i don't know !
In certain cases, that curls several times on the drop function ...
I can send you a zip with my code if you can help me please.
Sorry for my english.
Arthur Barbaray