wanted the help of the gentlemen. I am with a little bang on my neon kde 15.5. in the previous version 5.13 / 5.14 it ran all ok and after updating can not drag and drop mp3 files directly in the mixxx player, in other GTK distros everything is ok.
Can you help me ? the neon kde is the only distro that was perfect in the HP-probook 4430s. Since I thank everyone's attention.

I will only answer with this one posting:

1) KDE Plasma is QT-based

2) "apt show mixx" shows QT-dependencies,
and/but nothing at all regarding GTK.

What are You talking about?