code: @Override
  	public void setElementAt(E obj, int index) {
  		int idx = getRealIndex(index);
  		super.setElementAt(obj, idx);
  	}
docs: Sets the component at the specified index of this vector to be the
  specified object.
  
  @param index
  the index at which the element will be placed; it can be a positive
  number, or a negative number that is smaller than the size of the vector;
  see {@link #getRealIndex(int)}.
  @param element
  the new value to store at the specified index.
  @see java.util.Vector#setElementAt(java.lang.Object, int)