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 whether the output format is for printing
	 */
	protected boolean isForPrinting( )
	{
		String outputFormat = getOutputFormat( );
		if ( "FO".equalsIgnoreCase( outputFormat )
				|| "PDF".equalsIgnoreCase( outputFormat ) )
			return true;
		return false;
	}
	/**
	 * handle an extended item.
	 * 
	 * @param content
	 *            the object.
	 */
	protected IContent processExtendedContent( IForeignContent content )
	{
		assert IForeignContent.EXTERNAL_TYPE.equals( content.getRawType( ) );
		assert content.getGenerateBy( ) instanceof ExtendedItemDesign;
		IContent generatedContent = content;
		
		ExtendedItemDesign design = (ExtendedItemDesign) content
				.getGenerateBy( );
		ExtendedItemHandle handle = (ExtendedItemHandle) design.getHandle( );
		String tagName = handle.getExtensionName( );
		
		if ( "Chart".equals( tagName ) )
		{