code: @Override
  	public int indexOf(Object o, int index) {
  		int idx = getRealIndex(index);
  		return super.indexOf(o, idx);
  	}
docs: Returns the index of the first occurrence of the specified element in
  this vector, searching forwards from index, or returns -1 if the element
  is not found.
  
  @param o
  the object to look for.
  @param index
  the index from which to start the lookup; it can be a positive number,
  or a negative number that is smaller than the size of the vector; see
  {@link #getRealIndex(int)}.
  @see java.util.Vector#indexOf(java.lang.Object, int)