getForDrag  
  Gets the GtkDragIcon in use with @drag.
If no drag icon exists yet, a new one will be created and shown.
Return
the GtkDragIcon
Parameters
drag
a GdkDrag
Gets the GtkDragIcon in use with @drag.
If no drag icon exists yet, a new one will be created and shown.
the GtkDragIcon
a GdkDrag