Comment # 26 on bug 920792 from Ludwig Nussel

I just had a similar situation within 42.2. Suddenly dolphin, digikam etc had
no icons anymore when run in WindowMaker. I thought this worked initially, so
probably broke with some update. Not sure whether to recycle this bug but since
it's still open...
We need a proper solution that works out of the box for this. It's quite non
obvious having to install qt5ct and run it once to make KDE applications look
proper. So far qt5ct even interfered with a KDE session which made it even less
acceptable (sr#492216).