reFit/unZoom ?

[eil]

as probably most of users i have "Fit to .." setting enabled, so many of images are shown in smaller size. after using zoom, the only way to get back to usual whole-image view that i'm aware of, is go to next image and back. is there any command/button to do reFit?
by the way, it could be very useful if such feature appear in mouse buttons settings.