I have Ubuntu 16.04 LTS, and I installed
gnome-desktop. Everything works fine, except when I want to use a dual-screen: my cursor remains on the screen when I move it. I couldn't take a screenshot because it refreshes the page, so I just have this bad picture to show you:
Everything works fine when I use default settings (Unity), so I guess this issue comes from GNOME. If you have any idea, I'll be very grateful !