Dark kde plasma 5 session on Gentoo

Question

hI upgraded to KDE plasma 5.5.5 following the KDE 4.11 Gentoo wiki page:

sddm works fine, I can start a working openbox session with it. (Yes sddm is in the video group)

However, when I start plasma, I get a dark screen with working a mouse and a limited krunner.

I have an extensive xorg logfile: http://pastebin.com/m0mHVXJq

I extracted some relevant lines from it:

QCoreApplication::arguments: Please instantiate the QApplication object first
QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.
kscreen: Failed to request backend: unknown error

I use openrc and a Nvidia GeForce GTX 760 with 361.28 driver version with 3 displays but two xscreens.

Answer 1

According to some similar existing bugs on KDE forums, Xinerama can break kde-plasma5, so if you have Xinerama enabled in Xorg's config file (in /etc/X11/xorg.conf ) , try to disable it. It will be in the Section "ServerLayout" :

Option "Xinerama" "1"

So if you have the line like above, change the value to zero:

Option "Xinerama" "0"