ok thanks for pointing that out! i wasn't aware that XY has a combo option like that. i was expecting XY to simply have dedicated image fitting options like xnview.
i think the advantage of xnview's approach of having dedicated image fitting options instead of comboing, is that it lets you set a preferred dedicated image fitting option that is used by default whenever an image is opened--something that i wish XY had. because sometimes you want to just change the image fitting option temporarily for the current image, and it would be convenient if it can auto reset back to your preferred image fitting option for the next image, without having to manually do it.
example screenshot from xnview...
