code: public void addSelectionChangedListener(ISelectionChangedListener listener)
  	{
  		if (fOutlineViewer != null)
  		{
  			fOutlineViewer.addSelectionChangedListener(listener);
  		} else
  		{
  			fSelectionChangedListeners.add(listener);
  		}
  	}
docs: /*
  @see ISelectionProvider#addSelectionChangedListener(ISelectionChangedListener)