I'll include a pic of what I mean to clarify:
That very wide monitor on the right is actually two physical monitors. The graphics card just treats them as one monitor.
Obviously this is pretty annoying since I can only full-screen things on the far left monitor.
I've been googling for a solution to this for some time and have given up a few times. I tried using fakexrandr but that just made a total mess and I had to ssh in to fix that.
I've seen people suggest using tiled window managers for this, but that doesn't seem like a great solution.
It feels like telling the unity "treat this as two separate desktops" shouldn't be too hard. I've consistently failed to find a solution though.
I'm currently on Ubuntu 16.10 using Unity window manager.