What is "Zoom Canvas" supposed to do ("mag" command)

I tried mapping a shortcut key to the "Zoom Canvas" action (internally called "mag") and activating it crashes MuseScore, not surprisingly given it has no implementation. But did this work in previous versions, and what is it supposed to do? The only mentions I could find online are from many years ago. A "magnifying glass" function does seem like it might be useful...