Not sure if this help, but I am using a combination of XFCE/i3 - basically i3 with some xfce applets - and since upgrading to 14.04 I had trouble with i3 exiting normally when I close the lid (i.e. my Window manager dying). It seems closing the lid does not just close the backlight, but shuts down the whole display. Whether systemd is in control or xfce4-power does not seem to matter
Not sure if this help, but I am using a combination of XFCE/i3 - basically i3 with some xfce applets - and since upgrading to 14.04 I had trouble with i3 exiting normally when I close the lid (i.e. my Window manager dying). It seems closing the lid does not just close the backlight, but shuts down the whole display. Whether systemd is in control or xfce4-power does not seem to matter