code: protected void removeSource (JComponent comp)
      {
          if (_sourceComp == comp) {
              // reset cursors
              clearComponentCursor();
              _topComp.setCursor(_topCursor);
              reset();
          }
          _draggers.remove(comp);
          comp.removeMouseListener(_sourceListener);
          comp.removeMouseMotionListener(_sourceListener);
      }
docs: Remove a dragsource.