Bug 193886 NPE is thrown when preview external CSS style in ppt[1205]
engine/org.eclipse.birt.report.engine.emitter.ppt/src/org/eclipse/birt/report/engine/emitter/ppt/PPTRender.java
pptOutput.write( "<meta http-equiv=3D'Content-Type' content=3D'text/html; charset=3Dutf-8'>\n".getBytes( ) ); 
			pptOutput.write( "<meta name=3D'ProgId' content=3D'PowerPoint.Slide'>\n".getBytes( ) ); 
			pptOutput.write( "<meta name=3D'Generator' content=3D'Actuate View Server'>\n".getBytes( ) ); 
			pptOutput.write( "<title>Actuate Report</title>\n".getBytes( ) ); 
			pptOutput.write( "<xml><o:DocumentProperties>\n".getBytes( ) ); 
			pptOutput.write( "<o:Author>Actuate View Server</o:Author>\n".getBytes( ) ); 
			pptOutput.write( "</o:DocumentProperties></xml><link rel=3DFile-List href=3D'file-list'>\n".getBytes( ) ); 
			pptOutput.write( "<link rel=3DPresentation-XML href=3D'presentation'>\n".getBytes( ) ); 
			pptOutput.write( "</head><body/></html>\n".getBytes( ) ); 
		}
		catch ( IOException e )
		{
			e.printStackTrace( );
		}
	}
	/**
	 * Closes the document.
	 * 
	 * @param rc
	 *            the report content
	 */
	public void end( IReportContent rc )
	{
		if ( pptOutput != null )
		{
			try
			{
				pptOutput.write( "--___Actuate_Content_Boundary___\n".getBytes( ) ); 
				pptOutput.write( "Content-Location: file:/C:/___Actuate___/presentation\n".getBytes( ) ); 
				pptOutput.write( "Content-Transfer-Encoding: quoted-printable\n".getBytes( ) );