How to get startPosition when Drag a widget (vaadin 8.3)?

I have a component in a panel, with DragSourceExtension, I can pass any data by DragData, but I can not get relativeX and Y with DragStartEvent.

  • I can get relativeX and Y of end position with DropEvent.

In vaadin 7, with DragAndDropWrapper.WrapperTransferable (transferable), we can get relativeX and Y when start draging:

  • transferable.getMouseDownEvent().getClientX()
  • transferable.getMouseDownEvent().getClientY()