When is "Panning" in nvidia-setting useful?

So there’s a “Panning” option in nvidia-setting, which allows me to set a size only larger than “ViewPortIn”.

For example, if I set a 3840x1080 Panning for a 1920x1080 ViewPortIn, then I basically implemented some primitive “boss mode” (or “porn mode” :P) so that when I move the cursor to the right I can “pan” it to the extra black area (“1920x1080” on the right) to hide my desktop.

https://ptpb.pw/cJI-.png

I am curious, is this the only use case of “Panning”? It seems sort of silly to me and I don’t understand why it existed as an option. Obviously it’s not for TV overscan thing (coz that’s dealt with ViewPortIn AND ViewPortOut), so is there any purpose for it?

Oh nvm. Seems I was just unaware of the fact that the “extra black area” is actually usable desktop area, because I am using i3-wm…