> > How do I change the key mapping for moving to the Next/Prev image when viewing an image?
>
> In the viewer's menu: View | Customize | Tab:Keyboard | Category:File. Not all assignments are possible, but I tried '[' and ']' and that worked fine.
Why would the arrow keys be purposefully excluded?
> > The natural keys are the left/right arrow keys, or even the mouse wheel.
>
> No. Not all keyboards even have (easily accessible) arrow keys, which disqualifies them as default keys for core navigation functions. For image viewers and media players, Space has been the 'next' or 'play' button since before the days of Windows; you'll find the same Space/Backspace assignments in Irfanview and other programs.
>
To be clear, I didn't ask the defaults to be changed. I recognize not everyone has the same needs as I have, nor the same preferences. All I was requesting is to be able to set the mapping to my preference (arrow keys). Since this is primarily an image viewing program, I assumed moving between images was the primary workflow. Being able to set the Next/Prev key mappings would be a primary requirement.
> Anyway, with Numlock on, you can also use the left and right arrow keys if you prefer those.
In the same way that some of the keyboards you've encountered don't have arrow keys, my keyboards don't have numlock or a number pad. Only arrow keys.