The users in some forum I am currently helping run were complaining about the modified behaviour of image on image-page links since I updated from 0.4 to the latest version of the gallery. To sort that out, I re-implemented the old Facebook-like behaviour, where each image has a next image-page link. I did it by adding a new mode in generate_image_link, with two new optional function arguments, and putting a corresponding option in the acp gallery config. It's selected by Configure Gallery->Link Configuration->Image on Image-page->Open Next Image-page.
If anyone is interested, I can post the changes.