Been looking at Plasma 5. I had in the past and gave up.  I'm about to now too.  In the center of my screen it says (rough):

plasma 5 could not start process unable to create io-slave klauncher said unknown protocol file

When I go to change wallpapers (folder for the slideshow) it gives me three popup boxes telling me errors.  When I try to select the folder with all my wallpapers it won't allow that.  Nothing happens. 

There are other annoyances too,  Can''t drag an icon from the kicker menu to the panel to set up icons there.  When I try to drag one down it enlarges the space, slides the task bar over but won't show the icon.  Can't slide the taskbar back to the left unless I choose the burger menu on the far right bottom in the system tray area.

There are many more.  This is just the start.  Is this alpha software?  I've plasma 5.2 installed from the kubuntu ppa next-backports.

No app allows for "set wallpaper".  When