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

[Mathieu Othacehe]

Hello Ludo,

> Ouch.  Are there possible other such issues lurking?

The problem occurs when using `procedure->pointer' and passing the
returned pointer to a C library that stores it globally. Because, in
that case the pointer can be collected from the Guile side and used
later-on from the C side.

I fixed the two problematic patterns in Guile-Newt. Guile-Git seems to
be safe, but there might be an issue with Guile-Parted in
`exception-set-handler' method. I will investigate it.

>
>> Now I pushed a 'wip-installer-help' branch that implement this
>> mechanism. I'm now able to switch the installer keyboard layout from any
>> step.
>
> Woohoo, awesome!

Thanks :)

Mathieu