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/data/dte/ReportQueryBuilder.java
{
		
		public Object visitTemplate( TemplateDesign template, Object value )
		{
			return null;
		}
		
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.birt.report.engine.ir.ReportItemVisitor#visitFreeFormItem(org.eclipse.birt.report.engine.ir.FreeFormItemDesign)
		 */
		public Object visitFreeFormItem( FreeFormItemDesign container,
				Object value )
		{
			BaseQueryDefinition query = createQuery( container, value );
			for ( int i = 0; i < container.getItemCount( ); i++ )
				build( query, container.getItem( i ) );
			finishVisit( container, query );			
			if ( query != value )
			{
				return new IBaseQueryDefinition[]{ query };
			}
			return null;
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.birt.report.engine.ir.ReportItemVisitor#visitGridItem(org.eclipse.birt.report.engine.ir.GridItemDesign)