code: function changeOptionPosition( combo, steps, documentObject )
  	{
  		combo = getSelect( combo );
  		var iActualIndex = getSelectedIndex( combo );
  		if ( iActualIndex < 0 )
  			return false;
  
  		var iFinalIndex = iActualIndex + steps;
  		iFinalIndex = ( iFinalIndex < 0 ) ? 0 : iFinalIndex;
  		iFinalIndex = ( iFinalIndex >= combo.getChildCount() ) ? combo.getChildCount() - 1 : iFinalIndex;
  
  		if ( iActualIndex == iFinalIndex )
  			return false;
  
  		var oOption = combo.getChild( iActualIndex ),
  			sText	= oOption.getText(),
  			sValue	= oOption.getValue();
  
  		oOption.remove();
  
  		oOption = addOption( combo, sText, sValue, ( !documentObject ) ? null : documentObject, iFinalIndex );
  		setSelectedIndex( combo, iFinalIndex );
  		return oOption;
  	}
docs: Moves the selected option by a number of steps (also negative).