I am about to buy a 4K laptop and I would like to run Ubuntu 15.10 on it. I believe that shouldn't be a big problem. I'm sure I can adjust the text and the Unity UI just right.
The thing is that I use VirtualBox quite often for running Ubuntu Server on it. I believe to run into problems here. When not yet set, the text within the guest operating system should be small and barely readable, right? Is there any way to do some scaling of the guest os view? Like for instance scale it by the factor of times 2? Is it possible to run applications that do not adapt to 4k with a kind of magnifying lens? Like for instance running VirtualBox with some double-size zoom?