Gnome shell, media keys and strange X11 cursor bihaviour

Question

Hi guys,
I'm new in this forum, but old arch-user. This time I'm experimenting a really strange issue.
I have a lot of packages installed (pacman, but AUR too), and I tried some beta packet, so I don't know if this issues is caused by me, or is a sort of out-of-the-box, but this is what happens:
During Gnome-Shell session (3.16.2 actually), if I press any media keys (my keyboard has prev-next song, play/pause, stop, vol up-down) my cursor goes hidden (all works, but I can't see pointer). If I'm in empty desktop (no opened window), after 20~50pixel in any direction I can meet again my mouse. Instead, if I have some windows open...random behavior...cursor could reappear after 50pixel mouse movement, or it could stay hidden after 4-5Kpixel. The only way to get cursor again in short time is go to gnome overview (the function linked with super key or upper-left corner, by default).
Additional strange facts:
- mouse is working all the time (link is focused, button is pressed, focus follow mouse event, and so on...)
- seems gnome top bar get same effect as empty desktop (20~50pixel and cursor is visible again)
- if I link key combination with media function (Ctrl + Up/Down for volume, for example), everything goes well
- I have a secondary bluetooth keyboard with same media keys, but this peripheral is not affected by this issue
Any additional informations will be provided, but first, I did my homework:
- main keyboard: Thermaltake Tt eSPORTS Challenger Ultimate
- secondary keyboard: Logitech diNovo Mini
- main mouse: Kensington Expert Mouse
- secondary mouse (secondary keyboard has build-in touchpad): Logitech diNovo Mini
- tertiary mouse: Logitech G9x
- Gnome shell: 3.16.2
- X.Org: 1.17.1
- Kernel: 4.0.4-2-ARCH
- Nvidia-driver (beta from AUR): 352.09  --- GPU: GeForce GTX 780
- xinput output:
⎡ Virtual core pointer id=2 [master pointer (3)]
⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
⎜ ↳ Kensington Kensington Expert Mouse id=10 [slave pointer (2)]
⎜ ↳ Thermaltake Tt eSPORTS Challenger Ultimate gaming keyboard id=9 [slave pointer (2)]
⎜ ↳ Logitech diNovo Mini id=13 [slave pointer (2)]
⎜ ↳ Logitech G9x Laser Mouse id=14 [slave pointer (2)]
⎜ ↳ Logitech G9x Laser Mouse id=15 [slave pointer (2)]
⎣ Virtual core keyboard id=3 [master keyboard (2)]
↳ Virtual core XTEST keyboard id=5 [slave keyboard (3)]
↳ Power Button id=6 [slave keyboard (3)]
↳ Power Button id=7 [slave keyboard (3)]
↳ Thermaltake Tt eSPORTS Challenger Ultimate gaming keyboard id=8 [slave keyboard (3)]
↳ UVC Camera (046d:09a4) id=11 [slave keyboard (3)]
↳ Eee PC WMI hotkeys id=12 [slave keyboard (3)]
From this output I noticed some strange association: main keyboard apper as pointer too. Moreover if I kill id=9
xinput set-prop 9 "Device Enabled" 0
all keyboard still works, but media keys.
- xev output for volume key:
FocusOut event, serial 37, synthetic NO, window 0x3600001,
mode NotifyGrab, detail NotifyAncestor
FocusIn event, serial 37, synthetic NO, window 0x3600001,
mode NotifyUngrab, detail NotifyAncestor
KeymapNotify event, serial 37, synthetic NO, window 0x0,
keys: 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
randomly last 3 row become
KeymapNotify event, serial 38, synthetic NO, window 0x0,
keys: 4294967207 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
I already tried to use xmodmap (remapping), xdotool (scripting mouse movement), dconf ([...].gnome cursor active false), sddm (instead of gdm), and a ton of other trick found somewhere, but no luck.
Any idea? :-]
Thanks in advance

Answer 1

Got is sorted myself.
I installed KDE which worked perfectly. Then went about trying to install chromium. After installing and trying to launch chromium I noticed it would just hand unless launched by root (terminal).
Which led me to check permissions under /home.
Turns out that somehow my /home/{me}/.config directory was owned by root:root  . A simple chown -R ~/.config  and a reinstall of gnome got everything working fine 
NB: maybe someone with more insight can figure how/why ~/.config was owned by root from a fresh install and setup of systemd ??