It's 2019 and still nada. I remember doing this on KDE a long time ago. Could have been 3.5 or something. Winblows and OSX as well as other DEs like XFCE have it.
It really can't be that hard, can it? Same thing goes for Live Wallpapers. Microsucks used to call it "active wallpapers" back in the day. Android( a Linux distro fyi) has
it and we still have zilch. WTF is going on over there? You've had over 10 yrs to work on it. I would like to see these things implemented before I collect social security.