The default behavior in the Nexus 7 Image is to log straight in to the default user's desktop, bypassing the lightdm greeter. This seems like an acceptable behavior for testing the core but it's clearly insecure. I've changed the default password and would like lightdm to actually require the password to be entered, rather than just having a button that says "login". I've turned automatic login on and off in System Settings ? User Accounts but this doesn't help. Any suggestions?