The pdf and images preview in WPS is a feature included in eSchemes Deluxe edition.
http://www.ecomstation.it/ecsoft2/prog.php?progid=1405&name=eSchemes&sys=os2+ecomstation&language=en
http://www.ecomstation.it/ecsoft2/prog.php?progid=1405&name=eSchemes&sys=os2+ecomstation&language=en