Implements DND for data collections.
|$drag||the method is called when a drag operation is initiated|
|$dragDestroy||called when drag has been completed|
|$dragIn||the method is called when an item is moved into a possible drop landing during dnd|
|$dragMark||called during drag-n-drop, when some item of the component should be marked as an active drop target|
|$dragOut||called when the mouse pointer has been moved out of the drop area|
|$dragPos||defines the position of a dragged item|
|$drop||the method is called when an item is dragged and dropped on a valid target|