When printing a pdf document, when the print page comes up, I click on options, then the options tab, but the duplex printing option is greyed out, even though in the print configure from system settings, there is the option for duplex printing. Reproducible: Always
Which version are you using?
$ okular --version Qt: 4.8.6 KDE Development Platform: 4.14.6 Okular: 0.21.3
Duplex is only enabled if the ppd of your printer supports duplex. Are you sure it does?
Yes. I can turn duplex on or off in the system settings>printer options. But it is grayed out on okulars print dialogue.
We don't do anything to enable/disable duplex, that is part of Qt code. I'd typically say that you should report the bug upstream but unfortunately Qt 4.x is no longer developed so well if you can try a Qt5 app and it still happens in there, yes report a bug in the qt5 bug tracker.