Issue with hold-trigger-key-positions when typing quickly

[jamescrosswell]

I've got bottom row mods configured with a colemak-dh layout using hold-trigger-key-positions so that the mods on the LHS of the keyboard only apply to keys on the RHS of the keyboard and vice versa. If I quicky press C + A, everything works as expected. However, if I quickly press C + A followed quickly by pressing some key on the opposite side of the keyboard (that is in the list of hold-trigger-key-positions), then the C key is treated as a Ctrl modifier over the A key... and my cursor jumps to the start of the line (which messes with my flow pretty substantially).

Ideas / Brainstorming

It would be possible to add another option to the ZMK firmware that would make it easier to avoid this... like a non-trigger-key-interrupts-hold option or something, so that if a non trigger key is pressed in between pressing a hold tap key and pressing a trigger key, even if it's within the tapping term, it chooses a tap over a hold on the hold-tap key.

[caksoylar]

Do you have hold-trigger-on-release enabled? It sounds like it might help here: https://zmk.dev/docs/keymaps/behaviors/hold-tap#positional-hold-tap-and-hold-trigger-key-positions

[jamescrosswell]

https://zmk.dev/docs/keymaps/behaviors/hold-tap#positional-hold-tap-and-hold-trigger-key-positions

I do yes... but if I'm typing a fairly common word like "can" and I type all three of those characters (including releasing the n) within the tapping term, I still see this behaviour. In my case the tapping term for the C/Ctrl key is 200ms. I'm not even a very fast typist using Colemak - I've been using it for about 4 months, so still at about 60wpm.

I could play with the tapping term, but then I get more false positives for the hold behaviour.

[jamescrosswell]

Hm... I think I might have misunderstood what was happening. After some more typing I realised the "go to start of line" behavior is happening because I'm too slow to release the C key before pressing the A key and it's treating it as an LC(A) keypress, even before I press anything on the right hand side of the keyboard.

This is strange because the A key is at position 10 on the keyboard, which is not in the list of hold-trigger-key-positions. As far as I understand, the hold behaviour for the C key should not be triggered in this situation.

I've worked around for the time by increasing the tapping-term-ms from 200 to 250 to compensate for my sluggish typing for that key sequence.

[caksoylar]

This is intended, if you exceed tapping term then the key positions filter doesn't apply. (Also mentioned in https://github.com/urob/zmk-config?tab=readme-ov-file#timeless-homerow-mods).

HRMs can never be solved perfectly with settings tweaks, at the end of the day your typing style also adjusts over time to be more precise and not linger on keys unnecessarily.

[jamescrosswell]

This is intended, if you exceed tapping term then the key positions filter doesn't apply.

OK.. .complex. So the tapping term does two things:

1. It determines whether a press and release is considered a hold or a tap
2. It determines whether the hold-trigger-key-positions you have configured will be ignored or not

It's a pity those aren't separate settings.