Is there a way to trap Alt/Control-Key?

A suggestion or asking for help.

# Problem description

In C (I don't know how portable is this, so I can be totally off here), you can do something like

printf("%d %d",getchar(), getchar());

and if one does a alt-f (or example), it will output 102 27. So this could be a way to catch Alt keys (useful when you want to pop up a menu).

Is there a way to do this currently, or is this a feature-request?

# Environment

Linux

Backend used: ncurses
* If using ncurses on linux, ncurses version? (run `grep "define NCURSES_VERSION " /usr/include/curses.h`)
6.1
* Current locale (run `locale` in a terminal).
en_US.UTF-8
* Cursive version (from crates.io, from git, ...)
0.9