I have a 2560*1440 monitor, and want to play a game at 1920*1080 or lower, with the image being centered on the monitor (at native 1:1 pixel). However, it is always stretched to full screen and things get ugly on wrong resolution. On Windows, it is very easy to change that setting in Radeon or Nvidia driver control panel. I cannot find the same place to do that on Ubuntu Cuttlefish.
What I need is something equivalent to No scaling option. Image for illustration purpose. I am using Radeon card with Mesa driver, however.