Note: this post has now been updated for 18.04 LTS.
Recently I got a new Dell Precision 5520 and a TB16 dock. It came with Windows 10, and as I was quick to learn, “10” is the number of minutes it took me to decide that I would rather use anything else. This is coming from someone who has been using Windows on all non-server machines since age 7. Given the available options, I went for Ubuntu Linux.
As it turned out, Linux came with its own set of problems, and 4K or HiDPI has below usable support no matter which OS you choose.
I will maintain this post with status updates on the issues listed so that others can reuse my solutions. Another reason is that a bunch of my coworkers have decided to follow suit upon seeing Windows 10 and this is the most efficient way of helping them with the issues they are about to face.
Current setup: Ubuntu GNOME 18.04 LTS, 4.15 kernel.