feat: 'Non-US \' on builtin keyboards

[ids1024]

'Non-US \' is not listed, since the PS/2 keycode for that is the same as 'Backlash'. The UI around non-US layouts could be improved, but that's already an issue and this at least makes it possible to set this mapping.

This does not add the PAUSE and SCROLL_LOCK keycodes that have been added to EC. At least with PAUSE, this is complicated since it won't work on older firmware, and we should probably test for that (#140).

Fixes #127.

[linuxgnuru]

If using an ISO keyboard with this and after several key presses the system will halt and even the power button is unusable.

com.system76.keyboardconfigurator.desktop[6572]: [ERROR] Failed to get matrix: WouldBlock

[ids1024]

Huh, all this does is set a keycode. I guess something may not be quite right in the EC firmware...

What laptop is that with, on what firmware version?

[linuxgnuru]

darp6, 2021-07-20_93c2809, but I wonder if it's an issue with upstream, I'll test with an unpatched one

[linuxgnuru]

ok, it might just be this darp6; using ansi and iso keyboards after typing a few keys it locks up

[linuxgnuru]

Used different laptop and ISO keyboard. If set to UK keyboard the # key works but the 'non-us #' key in either US or UK mode always uses '\' and never the '#' key.

xev -event keyboard shows the following when I press the ISO # and the keyboard configurator 'Non-US #'

KeyRelease event, serial 28, synthetic NO, window 0xf400001,
    root 0x939, subw 0x0, time 1140218, (99,115), root:(139,310),
    state 0x0, keycode 51 (keysym 0x23, numbersign), same_screen YES,
    XLookupString gives 1 bytes: (23) "#"
    XFilterEvent returns: False

KeyPress event, serial 28, synthetic NO, window 0xf400001,
    root 0x939, subw 0x0, time 1144143, (99,115), root:(139,310),
    state 0x0, keycode 94 (keysym 0x5c, backslash), same_screen YES,
    XLookupString gives 1 bytes: (5c) "\"
    XmbLookupString gives 1 bytes: (5c) "\"
    XFilterEvent returns: False

[ids1024]

Hm, but K_BACKSLASH = K_INT_2, while this is using K_INT_2, so it seems strange that it would output that...

[ids1024]

Okay, I guess that's expected, since the \ key on the US layout generates # on UK? So they're swapped from what one might expect...

(We really need a UI that can adapt to keyboard layout.)