Oh sorry, I was really close … I changed opinion, now I’m sure. 
Installed Lx3 build 219 in a desktop and logout → login works.
Instead in netbook Acer Aspire One D270 logout → login don’t works.
Here is the “”“vbox issue”"" solved by @luca :
https://issues.openmandriva.org/show_bug.cgi?id=1582#c48
Luca, number1 !!! 
for those who are curious:
# cd /etc/dracut.conf.d
edit 50-dracut-distro.conf
add vboxvideo to the line beginning with add_drivers+=
save
# dracut -f
# reboot
I tried with Lx3 and dracut said it fails to install vboxvideo. I tried with different kernels: 4.5.0, 4.5.2, 4.6.0 and 4.6.1
What have I missed?
this is the line:
|# always include these modules
add_drivers+=" pata_acpi ata_generic ahci xhci-hcd ehci-pci ehci-platform ext4 reiserfs evdev hid usbhid cciss hpsa scsi_transport_spi mptbase mptspi mptscsih vboxvideo"
is X11-driver-video-vboxvideo installed?
I think you have to install also vbox-additions
Both, X11-driver-video-vboxvideo & dkms-vboxadditions, are installed.
here are mine:
/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko
/var/lib/dkms/vboxadditions/5.0.20-2/4.6.1-desktop-1omv/x86_64/module/vboxvideo.ko
and here is where dracut search for vboxvideo in my vm
# strace -f dracut -f 2>&1 | grep vboxvideo
[pid 19960] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 20623] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 20919] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 21089] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 21263] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 21287] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 21358] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 21376] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 21448] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 21484] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 31597] <… read resumed> “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 32037] read(0, “kernel/3rdparty/vbox/vboxvideo.k”…, 128) = 128
[pid 32692] execve(“/sbin/modinfo”, [“modinfo”, “-k”, “4.6.1-desktop-1omv”, “-F”, “filename”, “vboxvideo”], [/* 104 vars /]) = 0
[pid 32692] stat(“vboxvideo”, 0x7ffd75174ab8) = -1 ENOENT (No such file or directory)
[pid 32546] stat(“/var/tmp/dracut.40qa7p/initramfs/.kernelmodseen/vboxvideo”, 0x7ffef765a2f0) = -1 ENOENT (No such file or directory)
[pid 32693] execve(“/sbin/modprobe”, [“modprobe”, “–set-version”, “4.6.1-desktop-1omv”, “–ignore-install”, “–show-depends”, “vboxvideo”], [/ 104 vars */]) = 0
[pid 32694] stat(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, 0x7ffef7658de0) = -1 ENOENT (No such file or directory)
[pid 32694] stat(“/var/tmp/dracut.40qa7p/initramfs/.kernelmodseen/vboxvideo.ko”, 0x7ffef7658d10) = -1 ENOENT (No such file or directory)
[pid 32694] stat(“/var/tmp/dracut.40qa7p/initramfs//lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, 0x7ffef7658a70) = -1 ENOENT (No such file or directory)
[pid 32694] stat(“/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 32711] lstat(“/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 32711] stat(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, 0x7fffc75dc4f0) = -1 ENOENT (No such file or directory)
[pid 32711] lstat(“/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 32711] open(“/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_RDONLY|O_CLOEXEC) = 3
[pid 32711] open(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0644) = 4
[pid 32711] unlink(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”) = 0
[pid 32712] stat(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, 0x7fffe373ea40) = -1 ENOENT (No such file or directory)
[pid 32712] stat(“/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 32712] stat(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, 0x7fffe373e680) = -1 ENOENT (No such file or directory)
[pid 32712] open(“/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_RDONLY) = 3
[pid 32712] open(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_WRONLY|O_CREAT|O_EXCL, 0644) = 4
[pid 32694] open(“/var/tmp/dracut.40qa7p/initramfs/.kernelmodseen/vboxvideo.ko”, O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3
[pid 32714] stat(“/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 32714] stat(“/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 32714] open(“/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_RDONLY|O_CLOEXEC) = 3
[pid 2094] stat(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 2094] open(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_RDONLY|O_CLOEXEC) = 3
[pid 2095] unlinkat(4, “vboxvideo.ko”, 0) = 0
[pid 5598] open(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_RDONLY) = 3
[pid 5836] stat(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 5836] stat(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 5836] open(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_RDONLY) = 3
[pid 5836] lstat(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 5836] rename(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/st4bPZ3W”, “/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”) = 0
[pid 5836] chmod(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, 0644) = 0
[pid 5836] chown(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, 0, 0) = 0
[pid 5836] chmod(“/var/tmp/dracut.40qa7p/initramfs/lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, 0644) = 0
[pid 5930] lstat(“./lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, {st_mode=S_IFREG|0644, st_size=75960, …}) = 0
[pid 5930] open(“./lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_RDONLY|O_NONBLOCK|O_CLOEXEC) = 3
[pid 5930] open(“./lib/modules/4.6.1-desktop-1omv/kernel/3rdparty/vbox/vboxvideo.ko”, O_RDONLY) = 3
[pid 5933] unlinkat(6, “vboxvideo.ko”, 0) = 0
Are your guest additions properly working?
You are able to copy/paste host <-> guest and to share folders, yes?
I already looked in /lib/ but found nothing and no the guest additions don’t work properly. I was not worried till now.
But I just see that the version of virtualbox I use is 5.18 I downloaded once from the official site … and X11-driver-video-vboxvideo & dkms-vboxadditions are for 5.20 
I’ll install virtualbox 5.20 from the repos!
Ok, I found what I missed. I didn’t install the devel packages for the kernels and dms didn’t work, of course.
Now, I have installed the kernel 4.6.2 and its devel package.
I could force dracut to add the vboxvideo driver and … I get three small beautiful orange squares at start.
Hum, sometime one is white
I might need something else.
It’s a VirtualBox problem.
why don’t you install latest iso in a new vbox and install vbox-additions?
The reason is quite simple: my internet conectivity is very low and limited (3G) and I must go to a friend of mine to download big files… 
Plymouth also works often with the kernel 4.5.2 (without the vboxvideo driver).
Now try this:
reboot
urpmi --replacepkgs dkms-vboxadditions virtualbox-guest-additions
I tell you more. it works also in 2014.2 with kernel 4.1.18 and plymuoth 0.9.0 
I already did it with no more success, but if I saw that spinner is the default theme (in /usr/share/plymouth/plymouthd.default). I installed it and it worked. So I tried this:
plymouth-set-default-theme OpenMandriva -R
And that works even with the kernels for which I have not the vboxvideo driver.
Could someone confirm or invalidate?