Qemu, VNC and non-US keymaps

[B3r3n]

Dear all,

I am struggling for days/weeks with Qemu and its VNC accesses...with 
non-US keymaps.

Let me summ the facts:
- I am using a french keyboard over a Ubuntu 18.04.
- I installed a simple Debian in a Qemu VM, configured with FR 
keyboard (AZERTY).
- I am launching the Qemu VM with the '-k fr' keymaping (original)
- I tested with Qemu 3.1.1, 4.2.0 & 5.0.0.

I fail to have the AltGr keys, critical to frenches (pipe, backslash, 
dash etc).
checking with showkey, I see the keys arriving properly (29+56, 29+100, etc).

Considering it might be a debian issue as well, I updated the 
qemu/keymaps/fr file to have bar directly with the 6 key (normally 
bar is AltGr + 6).
For an unknown reason, the '6' then no longer works (showkey shows 
nothing as well).

There might be something I miss, and the might also be some bug 
somewhere, or some missings.
For example, maybe X11 must be installed, even it unused (VNC client 
connects to Qemu VNC port directly), or whatever.

Any help appreciated :-)

Thanks

Brgrds