Valve has been contracting KDE devs to fix bugs and add features for years now, as KDE is the desktop environment on SteamOS.

Good to know, thanks. I was more involved in KDE in the past years, but I don't have that amount of time now, so I missed these things, I believe.

However, KDE rocks. My colleagues called me "a maniac" once when they see how I use that thing (i.e. Dolphin + KIO + fast window switches + multiple desktops).