When i try to made drag&drop from one textbox to another, the text is correctly copied but the textbox value is empty.
This is a fiddle made from another user that explain the problem:
http://zkfiddle.org/sample/22qriko/1-zk-textbox-value-empty-on-drag-and-drop

when after drag&drop i select the second textbox the value is set, otherwise not.