Yuri Khan <yuri.v.khan@gmail.com> wrote:
> On Sun, 2 Aug 2020 at 18:00, Alan Davis <alan3davis@gmail.com> wrote:
>> I hoped the Nkey rollover would mean key chords like Ctrl-b would work.

> N-key rollover does not matter at all. Modifier keys (Ctrl, Alt, Shift
> and whatever OS-specific fourth key you use) are always reported
> independently in the USB HID keyboard protocol.

FWIW, N-key rollover is not really about USB or protocols; itʼs about circuit of the keyboard.

It does matter, when you reconfigure modifiers in a human-friendly way, that is move one of the ‘controls’ (normally, the left one) closer to ‘space’ — under your thumb — (ctrl:swap_lalt_lctl setxkbmap(1) -option or equivalent).

Then, on many ordinary keyboards few combinations, that are in use in Emacs, are indeed get ‘ghosted’.  And M-C-b with inner M- and C- is a very likely variant.

Two-key chords can never be affected, of course.