I've installed XFCE to test this desktop environment, but when I decide to switch back to Unity, uninstalling the XFCE packages, the LightDM keeps equal like XFCE, and I want to restore the Unity one. I think that is called Unity Greeter. Can someone help me?
I installed xubuntu-desktop on top of normal Ubuntu 14.04. Then I also noticed that the greeter had changed. I still use the xubuntu desktop, but I changed the greeter back by adding a line