'tis a little thing, but currently doesn't seem possible, When I'm viewing images fullscreen, I almost never care about things like what sort of camera was used, the fstop, etc., but I'd love to know the filename. You're essentially "flying blind" in fullscreen mode, you have no idea where you are in a list of images when you exit out, you're always left where you've started. This(apart from the speed) is about the only thing keeping the viewer being as good as "the old" acdsee for me.
I suppose it could be added to the info overlay, but really, even it's own display on the lower right, perhaps with a default 'n' as a key equiv, would be perfect.
DT