As described in the manual, scale inner crops the display down, so it might cut off the edges but otherwise will be fine. It won't show bars, that's what the letterbox modes do.
Thanks for the reply! Yes i know that but that doesn't answer my question. My question is if i want it to be playable on a 2,560x1440 resolution and use scale inner , will a 1920x1080 background/layout be sufficient or do i need a 2560x1440 background/layout? Will I get white bars or anything? Both ratio's are 16:9