bug#40273: installer: No way to input Latin characters with non-Latin keyboard layouts

[Mathieu Othacehe]

Hey,

> I test the Newt-based Debian 10 installer via QEMU.  When I select
> English language with Arabic keymap, I can choose a key combination
> for switching the layout, Alt+Shift by default.  But I cannot choose
> between AZERTY and QWERTY, I always get QWERTY.

Defining such a combination could be an option too. I tried to implement
the mechanism I proposed, but had multiple problems:

* Shepherd is using /dev/console as an output and some messages are
  polluting the help line displayed at the bottom of the screen. I'm not
  sure how to solve it.

  Shepherd could poll /dev/log so that once syslog is available it stops
  using /dev/console.

* Guile-newt functions "newt-set-help-callback" and
  "add-component-callback" seem to be tripping over each other and I'm
  having a hard time trying to understand why.

Regardless of this keyboard layout issue, having a help menu for the
installer could be useful to display the shortcuts for instance.

Thanks,

Mathieu