No keysyms send on level 7+

[Dave Howorth]

On Wed, 9 Sep 2020 10:19:38 +1000
Adam Nielsen <a.nielsen at shikadi.net> wrote:

> > I have remapped
> > `CapsLock` to `Backspace`
> > `AltGr` to `ControlR`
> > `ControlR` to `AltR`,
> > 
> > Now if i type one of the next sequences, it will be well
> > interpreted :
> > • `ControlR` + `AltR` + `Backspace`
> > • `ControlR` + `AltL` + `Backspace`
> > • `ControlL` + `AltR` + `Backspace`
> > 
> > However if I type this one :
> > • `AltL` + `ControlR` + `Backspace`
> > 
> > xev will not see any input.
> > This one definitivly make me think it’s the firmware fault.  
> 
> If I understand correctly, you are saying that ControlR + AltL works,
> but the reverse (AltL + ControlR) does not.  It could be a firmware
> issue however it's also possible it can be a keymap issue.

How? If it's a keymap issue then xev still sees input. It simply maps
it differently.

> For example I have mapped ShiftL + AltR to be the Compose key.  This
> means when I use these two keys together, the order is important.  If
> I press ShiftL first then AltR I get the Compose key event, but if I
> press AltR first then ShiftL then I get the Alt+Shift layer active.
> 
> The reason is that when you press the first key in the combination,
> that key's shift level gets activated.  You then need to make sure the
> second key in the combination has an entry in that shift level in
> order to reach the target.
> 
> It sounds like you may have an entry in the ControlR level for what to
> do when AltL is pressed, but you may not have an entry in the AltL
> level for what to do when ControlR is pressed.
> 
> > The same scheme apply with small variations on others keys, for
> > example if I type `c` instead of backspace `Backspace` and add
> > `Shift` to the combinaisons, the exact same behavior happens.  
> 
> If you want to know for sure if it is a keyboard/firmware problem,
> change the mapping to some other keys.  Instead of mapping AltGr to
> ControlR, map say ShiftR to ControlR instead.  If you try a few
> different key mappings and you still have the same problem, it is more
> likely to be your layout at fault rather than the hardware.
> 
> > Is it something relatively common to found such a keyboard which
> > can’t take much combinaisons ?  
> 
> The combinations you have - two modifiers + letter - should work on
> pretty much any keyboard.  If you were using a non-modifier key then
> you could run into issues after holding 2-3 keys depending on the
> keyboard design.
> 
> You can also look into tools that dump Linux evdev events.  This would
> allow you to see the key press / key release events at the kernel
> level.  A firmware problem would mean that at some point pressing a
> key won't generate an evdev event, but if you are seeing evdev events
> but no Xorg key event, then it means it's definitely an issue with
> your Xorg keymap.
> 
> Cheers,
> Adam.
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