selectedColumnIndex = -1;
	private void refreshColumns( )	{		columns = DataSetManager.getCurrentInstance( )				.getColumns( currentDataSetName, false );		columnChooser.removeAll( );		if ( columns.length == 0 )		{			columnChooser.setEnabled( false );			columnChooser.setItems( new String[0] );			selectedColumnIndex = -1;		}		else		{			columnChooser.setEnabled( true );			for ( int i = 0; i < columns.length; i++ )			{				columnChooser.add( columns[i].getDataSetColumnName( ) );			}			columnChooser.select( 0 );			selectedColumnIndex = 0;		}		refreshValues( );	}