@udon @Misato @ryo "I want to zoom in and out with my mousewheel alone, and yet many configured it to switch images"
I really, really hate that. The wheel should always zoom. And like I mentioned, I just go with Viewnior. I enable "Fit To Window Mode" and disable the menu bar (because I don't need it, but not the toolbar, that is still useful sometimes) I think that's about it. Not sure if I changed any of the other settings. It has some, though, which is better than what most have, which is nothing.

You actually can change what the scroll wheel does, and what double-clicking does. Incredible, most image viewers don't even have that. It's also light and uses GTK2. You can change the bindings for GTK2 itself, so I guess you have that option. The only downside of it is that for some reason retarded new image formats are coming into existence. What is a webp anyway? Why does that exist? All I know is that Viewnior doesn't know that it is either.