LightDM Greeter Box Issue

Hello. I’m new to Ubuntu Mate, but I have used Linux (mostly debian-based distros) fairly regularly since 2009. I have been very happy with Ubuntu Mate (I gave up on Ubuntu desktop when Unity was introduced, and I wish I had tried Mate sooner), but I am having an issue to which I have been unable to find a good solution.

I’m running Ubuntu Mate 16.04.1 LTS 64 bit on a laptop, which I keep hooked up to my television with the VGA/RGB port. This might be what is causing the problem. I haven’t tested whether disconnecting the television solves the problem because I want to be able to keep the television hooked up to the laptop regardless of whether I am viewing the television screen.

The problem is that when I login through the lightdm greeter, and then later sign out, when I return to login again I get nothing but the background image. The greeter box is not visible on the laptop screen or the television. But if I enter my login password on the keyboard, I am able to login normally. I can’t see the greeter window, but I figured out that it is still present and I can login with my password, even though I can’t see what I am typing. I have tried alt-tab on the keyboard to see if perhaps the greeter window was just not in the foreground. It’s just not visible at all, no matter what I try. Not a big problem for me, since I am normally the only one accessing this system. But I am concerned about when other users want to get on there, and there is no way for them to switch users and login without rebooting. And if I really wanted to reboot my system a lot without a good reason, I’d stick with Windows.

I have searched other forums and found similar problems, but not exactly what I am experiencing. Has anyone else experienced this type of problem? Any suggestions on a solution would be greatly appreciated.

Lightdm allows for “multihead setup” in the “Lightdm GTK+ Greeter settings”, have you tried to play around in those options?
Reading from your other post, I’m not sure UbuntuServer + MATE = Ubuntu MATE.
I haven’t had that kind of problems on my multiple-monitor desktop setup.

I’ll check that out. Thanks for the suggestion.

Yes, I installed Ubuntu Server first, and then installed Ubuntu-Mate
desktop environment over it. I don’t understand why that would make a
difference, but perhaps that is why I am having that issue.