Changing the font style to medium and rebooting, the font changes to normal. Using the Ubuntu Medium font, KDE 5.10 reverts it back to normal, 4.x would keep it the style as medium. Reproducible: Always Steps to Reproduce: 1. Select Fonts 2. Change font to Ubuntu with style Medium for all General/Small/toolbar/Menu/Window title 3. restart KDE, fonts all revert to Regular style. Actual Results: KDE 5.10 doesnt remember medium font style. Expected Results: Should remember font style choice. Tried this on the Ubuntu 15.04 and Opensuse Tumbleweed, same results.
Added URL so you can see fonts change back.
Likely it's fixed in Qt 5.8.0: https://github.com/qt/qtbase/commit/5dd907bf639f43be7f2cdfdd44ec3795f1b31bf6
What's KDE 5.10? I'm confused. Could you please test against a more recent Qt release, so we don't waste time on something that has long been fixed in Qt? If the problem persists, please reopen this bug report with config files attached.