Bug 136241 [regression]Preview template in web viewer and pdf didn't get correct effect.
Description: Preview template items in web viewer and pdf didn't get correct effect. Steps to reproduce: 1. Create template items. 2. Preview in Web Viewer and pdf. Expected result: Same effect as in html. Actual result: In web viewer, see only blank box. In pdf, blank page.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/ContentCommand.java
if ( !slot.contains( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_CONTENT_NOT_FOUND );
		if ( !slot.canDrop( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_DROP_FORBIDDEN );
		
		
		if ( !content.canDrop( ) && !flag )
			throw new ContentException(
					element,
					slotID,
					content,
					ContentException.DESIGN_EXCEPTION_STRUCTURE_CHANGE_FORBIDDEN );
		
		
		if ( hasDescendents( content, slotID ) )
		{
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_HAS_DESCENDENTS );
		}
		
		ContentRecord dropRecord = new ContentRecord( module, element, slotID,
				content, false );
		ActivityStack stack = getActivityStack( );
		stack.startFilterEventTrans( dropRecord.getLabel( ) );
		
		try
		{
			doDelectAction( content, unresolveReference );