Installing qt5-style-plugins and export QT_QPA_PLATFORMTHEME=gtk2 works for me. Great! Thank you for the clue. But I believe that this must be enabled by default and absence of this package in the default installation is actually the bug.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1695618 Title: Qt5 apps don’t pick up the GTK+ style anymore To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qtbase-opensource-src/+bug/1695618/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs