Bug 206864 Error in IE using nested birt tags when reportContainer is IFrame
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/taglib/AbstractViewerTag.java
.getMessage( ResourceConstants.TAGLIB_NO_REPORT_SOURCE ) );
		}
		
		if ( viewer.getReportletId( ) != null
				&& viewer.getReportDocument( ) == null )
		{
			throw new JspTagException( BirtResources
					.getMessage( ResourceConstants.TAGLIB_NO_REPORT_DOCUMENT ) );
		}
		return true;
	}
	/**
	 * Validate the viewer id. Viewer id only can include number, letter and
	 * underline
	 * 
	 * @return
	 */
	protected boolean __validateViewerId( )
	{
		Pattern p = Pattern.compile( "^\\w+$" ); 
		Matcher m = p.matcher( viewer.getId( ) );
		return m.find( );
	}
	/**
	 * Handle event before doEndTag
	 */
	protected void __beforeEndTag( )
	{
		super.__beforeEndTag( );
		viewer.setParameters( parameters );