Until the new M manual is available, we can only speculate unless someone who has access to an evaluation sample can tell us explicitly.
Originally Posted by Guy Mancuso
I'd see the focus button on the front having two functions, depending on camera operational mode:
- with Live View off, the button changes framelines in the optical finder since they're now implemented with an LCD overlay. swap between framelines using the thumbwheel. default framelines are set by the lens' built in cam. (focus is confirmed using the rangefinder)
- with Live View on (either LCD or EVF), the button provides magnification and focus peaking (depending on menu based configuration for peaking and the thumbwheel for magnification changes)
That is what I'd want. Whether it's what Leica provided remains to be seen.