The MDM Setup tool was redesigned:
The new layout is similar to mintDesktop, with icons in the sidebar to access the different parts of the tool.
The concept of “greeters” was confusing to users so it was replaced by a simpler theme selection. All themes (HTML and GDM) as well as the GTK greeter are now available from the same list.
It’s also worth noting the addition of a new button (the one with the cog) to launch the login screen and thus quickly visualize the active theme.