Hi! someone I know is selling his EOS M but the back buttons don't work. Will I be able to access all the menus in ML through the touchscreen?
No.
Unless I misunderstand the question, I can access all ML menus via the EOSM touch screen.
Try Shoot screen -> Intervalometer -> Start Trigger
and try to get there without any button located on the back.
On travel at the moment but I will try when back home.
Cheers
Garry
If you are not afraid of the source code, here's a proof of concept (https://www.magiclantern.fm/forum/index.php?topic=18544.0).
A bit abandoned; I wrote and tested it on a borrowed 700D, hoping other developers would pick up and polish that code. Didn't happen.
In any case, touch screen can be used from ML; all it needs is some manpower to complete the proof of concept and turn it into something usable.
Just tried a touch-menu build on the EOSM and no, you can't get to all the ML menus. Note that it mostly works though it is a bit awkward trying to do everything from the touch screen. I find it faster using just the buttons. Depending on which buttons aren't working on the camera you won't be able to navigate the Canon menus either.
I did find the stub for the 1-finger drag gesture on the EOSM (https://bitbucket.org/hudson/magic-lantern/pull-requests/799/added-bgmt_drag_1_finger-for-eosm/diff) and 650D (https://bitbucket.org/hudson/magic-lantern/pull-requests/800/added-bgmt_drag_1_finger-for-650d/diff) but didn't go beyond that.
This does look like an interesting feature that deserves more attention. Especially now that most, if not all of the new cameras have touch screens.