I just tried your wallpaper option and now I wonder if you offer competition-product migration discounts because this is a killer feature! I wanted to span a single wallpaper across multiple monitors of different sizes and resolutions and of course the wallpaper is all messed up. But with the zoom and shift options, I can adjust the individual views of the wallpaper on each monitor to account for the resolution differences, placement, and even bezel gaps. So now my monitors feel like I'm looking out a physical window at a single scene.

But getting wallpapers to look correct takes a lot of trial-and-error. And often it only works well with wallpaper scenes that clearly have elements that run across the entire scene so you can easily compare the sizes and make sure things are aligned. It would be nice if DF has some sort of wizard to model the physical characteristics of the monitors so any wallpaper is automatically looking seamless across all monitors.

Maybe a combination of the below test can be used to gather geometry info:

• Zoom: For each monitor, show a square that you would use a real ruler to measure. Then show squares on the other monitors and have you adjust the height/width of those squares against a real ruler so all the squares are physically the same size.
• Alignment: For each monitor, draw horizontal and vertical guide lines from the edges of the monitor that span across the other monitors. Then on the other monitors, you would adjust the position of the lines so that line up with the original monitor.
  
• Bezel: Ask the user to measure and enter the bezel size of each edge of each monitor.

Bonus: use a webcam to track the user's head position and shift the viewpoint of the wallpaper based on the user's head position! Did a search and found this: Multi-monitor Window VR: https://www.youtube.com/watch?v=swNLzO3btKM
If we can do this for VR, certainly we can do it for a static wallpaper.