I am running a fresh install of openSUSE Leap 42.2 with the KDE desktop, i.e.
KDE Plasma version: 5.8.3
KDE Frameworks version: 5.26.0
Qt version: 5.6.1
Some KDE applications (e.g. okular, mozilla-kde4-integration, krename, etc.) still use
KDE Development Platform 4.14.25. The GUI of these applications is drawn using a different font (some condensed bold font) than the GUI of those which use the new KDE Frameworks 5 (Noto Sans 10). See the two images below for a comparison (okular vs dragonplayer).
I suspect that KDE4 apps might load their font settings from somewhere else (some legacy Plasma 4 config file?) than plain Qt4 apps configured by qtconfig. Do you have any idea on the font being used? We could then do a text search on the font name to find the corresponding config file… Unfortunately, I have no better idea
Inspired by your suggestion I installed kdebase4-workspace-addons package which provides /usr/bin/systemsettings. It does not conflict with its counterpart from KDE5, because in kde5 the executable is called systemsettings5. Anyway, I executed this newly installed systemsettings and it miraculously synchronized setting for KDE4 apps with those from KDE5.
Yes, I encountered the same problem. in my case, puddletag looked awful. I did find another solution which seems to be THE way KDE wants us to go: There is a “Qt4 Settings” entry under “Dienstprogramme” (sorry, don’t know the exact wording openSUSE uses in English) in the application starter (I have Tumbleweed). This app lets us change the font for Qt4 programs nicely.
Thanks for this thread. Without it, I wouldn’t have looked into “Qt4 Settings”.