Comment 1 for bug 1377743

Could you please test this fix:
https://code.launchpad.net/~kalgasnik/+archive/ubuntu/lightdm-gtk-greeter-lp1377743

Do not pay attention to some graphical issues (windows transparency) if you are using Greybird theme, it is trunk version and it isn't compatible with theme currently used in 14.04 or 14.10.