I did a fresh install of 16.04 recently, and to my surprise my second monitor worked pretty much out of the box with the nvidia driver 361.42. The HDMI is wired over the Quadro K1000M and that used to be a lot of trouble.
My issue now is that windows that are maximized, or worse in fullscreen, span across the two monitors (resulting in a 3840x1080 window). I have two launchers, but only one menubar with the applications menu on the left screen and the system menu on the right screen.
Is there a way to restore the old (and to me expected) layout / behavior?
DP-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 298mm panning 3840x1080+0+0 LVDS-1 connected primary 1920x1080+1920+0 344mm x 193mm