web.drag interfaces.

The DataTransfer object is used to hold the data that is being
during a drag and drop operation. It may hold one or more data
each of one or more data types. For more information about drag
drop, see HTML Drag and Drop API.

The DataTransferItem object represents one drag data item. During
drag operation, each `drag event` has a `dataTransfer` property
contains a `list` of drag data items. Each item in the list is
DataTransferItem object.

The DataTransferItemList object is a list of `web.drag.DataTransferItem`
representing items being dragged. During a drag operation, each
has a `dataTransfer` property and that property is a DataTransferItemList.

The DragEvent interface is a `DOM event` that represents a drag
drop interaction. The user initiates a drag by placing a pointer
(such as a mouse) on the touch surface and then dragging the
to a new location (such as another DOM element). Applications
free to interpret a drag and drop interaction in an application-specific