ViewDocumentDraggingEvent
typedef
Fired as a continuation of the event-dragover event.
It is a part of the clipboard input pipeline.
This event carries a dataTransfer object which comes from the clipboard and whose content should be processed
and inserted into the editor.
Note: This event is not available by default. To make it available, ClipboardObserver
needs to be added to the ViewDocument by using the
addObserver method. This is usually done by the
Clipboard plugin, but if for some reason it is not loaded,
the observer must be added manually.