Zoom (+ "Fit to view") to Preview panel

Some basic zooming ("fit to view" + pinch/scrollwheel) would be nice in the Preview Panel. I work on relatively small images, and the lack of "fit"/zooming keeps bugging me particularly on Mac Retina screens. 

I'm not sure what is the reason there is only this small magnifying glass thing (found very little use for it myself), and would definitely prefer zooming the whole image myself instead. I'm sure both can exist at the same time though.

Full Screen Preview supports zooming, but then it doesn't support custom keyboard shortcuts.