Inform GDK if the drop ended successfully.
Passing false for success may trigger a drag cancellation animation.
This function is called by the drag source, and should be the last call before dropping the reference to the context.
The DragContext will only take the first drag_drop_done call as effective, if this function is called multiple times, all subsequent calls will be ignored.
| context | |
| success |
whether the drag was ultimatively successful |