Change lock screen in mate-screensaver to be like LightDM

[philthynz]

I checked out the latest 17.10 build. The new “Slick” greeter using LightDM is really nice, love it.

But, the lock screen still looks ugly using mate-screensaver. That giant square in the middle just doesn’t look good after some effort went into changing the login screen. Can a new feature request be to drop the old one, and use the same style as the new LightDM?

[Robgoss]

@philthynz Yes I’m with you on that lock screen how can I change it to look as Ubuntu 16.04 I can live with that look

Thanks so much