Graphical components stuck on Kubuntu 16.04

Question

I have Kubuntu 16.04 with kde 5.6.5, and I cannot change the graphical components, I am stuck with the qtcurve style.

Here is a screenshot of the settings, as you can see, the style selected (and applied) is Fusion, but the qtcurve is still used.

I am using a laptop with intel graphics and nvidia card, and I had problems insalling drivers because of the optimus system. While trying to reinstall my graphics drivers, I ended up installing the ubuntu desktop on my system (I don't remember the exact command). On the login screen, I can now choose between plasma and Ubuntu.

I don't know if it's related, but I thought it was useful to mention it.

I tried rebooting, no luck.

This is not an urgent problem (qtcurve style is good), but this is annoying and I like having a working system :D

Any help is welcome.

Answer 1

Cause of the Problem

I experienced this same problem yesterday and discovered that, some packages was overriding QT style with gtk looks. The environment variables in question were QT_STYLE_OVERRIDE and QT_QPA_PLATFORMTHEME.

Solution

The solution is putting these lines in ~/.profile file to unset the environment variables.

## Fixing QT style override problem
if [ "x$XDG_SESSION_DESKTOP" == "xKDE" ] || [ "x$XDG_SESSION_DESKTOP" == "xplasma" ];
then
    unset QT_STYLE_OVERRIDE
    unset QT_QPA_PLATFORMTHEME
fi

Now, the style should be changeable and will persist.