code: protected void addSource (
          DragSource source, JComponent comp, boolean autoremove)
      {
          _draggers.put(comp, source);
          comp.addMouseListener(_sourceListener);
          comp.addMouseMotionListener(_sourceListener);
          if (autoremove) {
              comp.addAncestorListener(_remover);
          }
      }
docs: Add a dragsource.