Configure lightdm

Ubuntu 14.04

After remove unity and install xfce4 we still need to configure lightdm

Install lightdm greeter:

apt-get install  lightdm-gtk-greeter

Configure lightdm

  cat /etc/lightdm/lightdm.conf.d/50-imovefan.conf 
  [SeatDefaults]
  greeter-session=lightdm-gtk-greeter
  user-session=xfce4