On Kubuntu 15.04 and Fedora 22 with KDE spin, the Unify Displays works OK, but after re-login the Desktop Display for both displays will be changed.:

Kubuntu 15.04 has lost the widgets and the icons are now in alphabetical order.
Fedora 22 has completely lost the Desktop - Wallpaper only (in both cases the Panel is intact though)

Video http://youtu.be/PUW33XSKjik Written companion http://goo.gl/ISVTaJ
Help would be appreciated!

Solved with Plasma 5.7.5