–> http://askubuntu.com/questions/462428/14-04-trusty-tahr-lightdm-no-way-to-switch-session#comment609386_462428
apt-get install –reinstall gnome-session
dépot : https://extensions.gnome.org/
installées : https://extensions.gnome.org/local/
liste extensions usuelles :
Alt Tab Workspace by kwalo
Animation Tweaks by Selenium_H12345
Coverflow Alt-Tab by p91paul
Dash to Dock by michele_g
Desktop Icons by rastersoft
Gnome-Shutdown Button by kirby_33
Impatience by gfxmonk
Lock Keys by kazimieras.vaina
Remove Alt+Tab Delay by tetrafox
Services Systemd by petres
Tray Icons: Reloaded by MartinPL
User Themes by fmuellner
root : /usr/share/gnome-shell/extensions
user : ~/.local/share/gnome-shell/extensions
→ http://askubuntu.com/questions/455301/how-to-restart-gnome-shell-after-it-became-unresponsive-freeze/496999#496999
ctrl + alt + F1 et killall -3 gnome-shell
installer alacarte
lancer menu principal