Common feature of drag and drop is an image representing the data floating with the cursor during drag and drop operation. In FX this is called "Drag View" and is likely to be added to Dragboard. 

The API proposal:

Add methods to DragBoard:
void setDragView(Image image, double offsetX, double offsetY) // convenience method for the three calls
void setDragView(Image image) // typically used with event.getGestureSource().snapshot()
void setDragViewOffsetX(double offsetX)
void setDragViewOffsetY(double offsetY)
Image getDragView()
double getDragViewOffsetX()
double getDragViewOffsetY()

All those methods are to be used only during drag detection (in a DRAG_DETECTED event handler) and will have no effect or return nulls and zeros if called elsewhere.