not that I've tried any of this, but pure-pdf seems to be based off of
IText, and as such most of the features of the IText API correspond to
pure-pdf...
Doing a quick google search I found the following...
http://api.itextpdf.com/com/itextpdf/text/pdf/interfaces/PdfViewerPreferences.html
looks like you can set it in PdfViewerPreferences... I'm not anywhere
near where I can test that out however. Let me know if it helps
loogie