There are 2 errors on drag ghost from Tree / Treeitem component.
1- On multiple selection, only the dragged item text is showed. This behavior is different from Listbox. In Listbox when more than one element is dragged, for each element one ghost element is generated. I expect that the behavior must be the same in both components.
2- When the Tree has Treecols, the drag message generated is one concatenation of all Treecells. On Listbox the drag message is generated only with the content of the first cell.
Please verify if this issues, and give me some estimate date for the bug fix.

ZK fiddle example: http://zkfiddle.org/sample/1241f3b/2-Bug-drag-and-Drop-Tree
Jing capture in attachment.

In attachment one screenshot of the problem.
Thanks,
My Best Regards,