I am using the kubuntu next repository on kubuntu 14.10 - with the latest release of plasma 5.1. I have a bizarre issue that the kf5 applications like system-settings seem to be using the gtk2 theme set using the kde-gtk-config tool. Kde4 applications and qt4 applications correctly use the application style set.

E,g, i set application style to breeze, gtk2 theme to qtcurve and gtk3 to adwaita - and i can see that systemsettings5 is using qtcurve. while konversation (kde 4) and cadence (qt4) is using breeze (qt4config shows that theme is set to desktop default).

When i change the gtk2 theme to say oxygen-gtk and restart system-settings it changes themes.

Changing the theme in kde application style doesn't have any effect on system settings - also i that kde 4 applications don't change themes on the fly - they need to be restarted which is different behaviour to what i had seen in the early betas of plasma next

Please let me know how i can debug this issue further?

Output of lsb_release -rd

Description: Ubuntu Utopic Unicorn (development branch)
Release: 14.10

output of apt-cache policy plasma-workspace

plasma-workspace:
  Installed: 4:5.1.0-0ubuntu1~ubuntu14.10~ppa4
  Candidate: 4:5.1.0-0ubuntu1~ubuntu14.10~ppa4
  Version table:
 *** 4:5.1.0-0ubuntu1~ubuntu14.10~ppa4 0
        500 http://ppa.launchpad.net/kubuntu-ppa/next/ubuntu/ utopic/main amd64 Packages
        100 /var/lib/dpkg/status

Reproducible: Always

Steps to Reproduce:
1. start system settings
2. change the gtk theme to say redmond
3.restart system settings - the gtk theme is used for the kf5 application
4. kde 4 applications remain unaffected

Actual Results:  
kf5 applications use gtk2 theme

Expected Results:  
kf5 application should use the kde application style theme

i have pasted the launchpad bug report link with a screenshot in the url section