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( "Content-Type: text/xml; charset=\"utf-8\"\n".getBytes( ) ); 
				pptOutput.write( "\n".getBytes( ) ); 
				pptOutput.write( "<xml\n".getBytes( ) ); 
				pptOutput.write( " xmlns:o=3D'urn:schemas-microsoft-com:office:office'\n".getBytes( ) ); 
				pptOutput.write( " xmlns:p=3D'urn:schemas-microsoft-com:office:powerpoint'\n".getBytes( ) ); 
				pptOutput.write( ">\n".getBytes( ) ); 
				pptOutput.write( ( "<p:presentation sizeof=3D'custom' slidesizex=3D'" + ( pageWidth * 8 ) + "' slidesizey=3D'" + ( pageHeight * 8 ) + "'>\n" ).getBytes( ) ); 
				for ( int i = 0; i < currentPageNum; i++ )
				{
					pptOutput.write( ( "<p:slide id=3D'" + ( i + 1 ) + "' href=3D's" + ( i + 1 ) + "'/>\n" ).getBytes( ) ); 
				}
				pptOutput.write( "</p:presentation></xml>\n".getBytes( ) ); 
				pptOutput.write( "\n".getBytes( ) ); 
				pptOutput.write( "--___Actuate_Content_Boundary___\n".getBytes( ) ); 
				pptOutput.write( "Content-Location: file:/C:/___Actuate___/file-list\n".getBytes( ) ); 
				pptOutput.write( "Content-Transfer-Encoding: quoted-printable\n".getBytes( ) ); 
				pptOutput.write( "Content-Type: text/xml; charset=\"utf-8\"\n".getBytes( ) ); 
				pptOutput.write( "<xml\n".getBytes( ) ); 
				pptOutput.write( " xmlns:o=3D'urn:schemas-microsoft-com:office:office'\n".getBytes( ) ); 
				pptOutput.write( " xmlns:p=3D'urn:schemas-microsoft-com:office:powerpoint'\n".getBytes( ) ); 
				pptOutput.write( ">\n".getBytes( ) ); 
				pptOutput.write( "<o:MainFile href=3D'slide-show'/>\n".getBytes( ) ); 
				pptOutput.write( "<o:File href=3D'presentation'/>\n".getBytes( ) ); 
				pptOutput.write( "<o:File href=3D'file-list'/>\n".getBytes( ) ); 
				for ( int i = 0; i < currentPageNum; i++ )
				{
					pptOutput.write( ( "<o:File href=3D's" + ( i + 1 ) + "'/>\n" ).getBytes( ) ); 
					if ( fileNamesLists.containsKey( new Integer( i + 1 ) ) )
					{
						List filenames = (List) fileNamesLists.get( new Integer( i + 1 ) );