Also it's not possible to use Pgup / Pgdn to move the image around quickly.
I have lots of images to view which have a lot of white space, and the important part is in the middle...but when the zoom is high.....the important detail is off screen and needs to be scrolled into view.
The up/down arrows are too slow, and the only way to get it into view is to use the mouse to drag the image - not convenient.
Ssupport pgup / down (let them be mapped to zooming instead of navigation of files), or have a way to position the image to the detail i.e. it ignores white space (by some detection algorithm).....use some kind of auto crop algorithm to detect the "important" part of the image....to aid positioning.