After an upgrade to ubuntu bionic and the latest KDE applications distributed for this platform, I am experiencing an issue with okular. Whenever I open the okular print dialog the duplex option is preset to none for all printers, even those where long edge duplex is the default at the system level. This is an issue that leads to a huge waste of paper whenever one forgets checking. I strongly suspect that the issue is with the QT print dialog rather than with okular, but I am anyway asking here for an informed opinion. Incidentally, I really think that KDE should move away from the extremely poor qt print dialog as it was in the past, because from the qt dialog no printer properties can be controlled (print quality, ink consumption, paper type, stapling, etc.), which means keeping a non qt pdf reader around for any pdf print need that requires some control over the printer.
Yep, it's a Qt issue: https://bugreports.qt.io/browse/QTBUG-3567 I understand and share your frustration with the Qt's subpar print dialog. However, the real solution here is to improve it so that all clients can benefit. Diverging from it in the past caused code maintainability issues. When the upstream code is lousy, we've just gotta do our part to improve it.
Nate that bug you pointed has nothing to do with what Sergio is describing. Sergio, which Qt version does Bionic ship? Because for the stapling etc you want to use Qt 5.11 https://www.kdab.com/better-support-for-cups-features-in-qt-5-11/ which i guess Ubuntu is not shipping because they always excel at shipping somewhat outdated stuff.
(In reply to Albert Astals Cid from comment #2) > Nate that bug you pointed has nothing to do with what Sergio is describing. I found https://bugreports.qt.io/browse/QTBUG-5196, which seems to describe Sergio's issue, and that's marked as a duplicate of the one I mentioned above. Is this wrong? > Sergio, which Qt version does Bionic ship? 5.9.5
Note how he says "the duplex option is preset to none for all printers, even those where long edge duplex is the default at the system level." That is "Qt print dialog doesn't read default options" it's not "it doesn't remember options from the last time you opened the dialog". I suggest you to use something with Qt 5.11 or newer, it should give you a much nicer print dialog experience, this bug is most probably fixed since I fixed several issues regarding the default option support.
Ah, thanks Albert. My mistake.
@ Nate, Albert, thanks for the clarification, I was almost sure that the issue was on Qt. And indeed, bionic is stuck at QT 5.9.5. Good to know that at least is a matter of waiting and that qt 5.11 has a better print dialog!
I've have played around a bit and backported the patch mentioned in the above bug report into ubuntu bionic packages. It seems to work fine. You may want to test it installing "libqt5printsupport5" from my ppa: https://launchpad.net/~rbredereck/+archive/ubuntu/qtbase-opensource-src-duplexpatch If people can approve that it works, we can start annoying the ubuntu maintainers to include the patch into the standard packages. PS: I know that is is also weakly related to the KDE bug. However, it is highly relevant to save wasting paper...