Disable Volume and Brightness OSD in KDE

A few days ago Arch linux team decided to dropout support for KDE 4, and force their users to upgrade to KDE Plasma 5. I've tested Plasma 5 around 10 months ago and, to be honest, my experience was not good, Plasma 5 suffered a lot of stability problems, but the problem that most annoyed me was the backlight OSD thing, i've even reported and suggested a patch for it but their developers ignored me and refused to fix this problem. So i had not option but to return to KDE 4.

Yesterday, i had not option but to try Plasma 5 again, and for my surprise (or not), the backlight OSD thing was not fixed, but also KMix is showing OSD again without option for disabling it, and it was supposed to have been fixed 3 years ago. A this point i don't know what KDE developers are thinking, it seems that their are trying to transform KDE into a Nagware. At least i know that i'm not alone because 3 months after my report, other user reported it again, and developers provided just a partial solution making the OSD smaller than before, but for me it was not ok and decided to get rid of the OSD annoyance once for all.