the method is called when an item is moved out of a possible drop landing during dnd
| source | HTMLElement | a DOM element from which a drag-n-drop action has started |
| old_target | HTMLElement | a DOM element of the drop from which an item has been moved out |
| new_target | HTMLElement | a new DOM element which will be used as a drop target (can be null) |
| ev | Event | a native HTML event |
The method is not purposed for direct call! It is an extension point.
You can override it with your own logic, but check drag-n-drop related events first, as they provide a much more convenient way for drag-n-drop handling.