Bug 166732 Duplicate id isn't handled in BIRT viewer tag.[0603]
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/taglib/AbstractViewerTag.java
if ( viewer.getReportletId( ) != null
				&& viewer.getReportDocument( ) == null )
		{
			throw new JspTagException( BirtResources
					.getMessage( ResourceConstants.TAGLIB_NO_REPORT_DOCUMENT ) );
		}
	}
	/**
	 * Handle event before doEndTag
	 */
	protected void __beforeEndTag( )
	{
		super.__beforeEndTag( );
		viewer.setParameters( parameters );
	}
	/**
	 * Handle use IFrame to preview report. Each IFrame should have an unique
	 * id.
	 * 
	 * @param src
	 * @param target
	 * @throws Exception
	 */
	protected void __handleIFrame( String src, String target ) throws Exception
	{
		JspWriter writer = pageContext.getOut( );
		writer.write( "<script type=\"text/javascript\">\n" ); 
		writer.write( "function loadViewer" + viewer.getId( ) + "(){\n" ); 
		writer.write( "var divObj = document.createElement( \"DIV\" );\n" ); 
		writer.write( "var bodyObj = document.body;\n" );