if ( !selection.isEmpty() )
        {
            String attribute = ( String ) selection.getFirstElement();
            AttributeDialog dialog = new AttributeDialog( addAttributeButton.getShell(), attribute,
                getAttributeNamesAndOids() );
            if ( AttributeDialog.OK == dialog.open() )
            {
                attributesList.remove( attribute );
                String newAttribute = dialog.getAttribute();
                if ( !attributesList.contains( newAttribute ) )
                {
                    attributesList.add( newAttribute );
                }