Bug 177504 Engine doesn't provide SubQuery for extended item
Engine doesn't provide SubQuery for extended item, so chart can't use container's binding to execute the query. If possible, engine could provide an option for extended item to choose whether engine could create the query, so extended item won't create SubQuery by itself.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/presentation/LocalizedContentVisitor.java
return table;
	}
	public Object visitRow( IRowContent row, Object value )
	{
		handleOnRender( row );
		return row;
	}
	public Object visitCell( ICellContent cell, Object value )
	{
		handleOnRender( cell );
		return cell;
	}
	/**
	 * handle the data content.
	 * 
	 * @param data
	 *            data content object
	 */
	public Object visitData( IDataContent data, Object value )
	{
		handleOnRender( data );
		processData( data );
		return data;
	}
	/**
	 * process the data content
	 * 
	 * <li> localize the help text
	 * <li> format the value
	 * <li> handle it as it is an text.