to avoid this problem, don't use restricted card driver : go to System / Admin / Restricted drivers and suppress non open-source driver. In other word, avoid gglrx and nvidia in /etc/X11/xorg.conf ; prefer nv and ati.
to avoid this problem, don't use restricted card driver : go to System / Admin / Restricted drivers and suppress non open-source driver. In other word, avoid gglrx and nvidia in /etc/X11/xorg.conf ; prefer nv and ati.