I will work on a fix now. Check back tomorrow for the file http://download.fop2.com/fop2.js and replace your current one with the updated I will make today (it will work only for fop 2.27 final).
EDIT: The patch is done, you can get the fop2.js file now if you want to test. Backup your original one just in case (/var/www/html/fop2/js/fop2.js).