Thumb wheel horizontal scroll can't be reversed: default binding pair is inverted vs. native scroll direction

[isleofgreg]

Thumb wheel horizontal scroll can't be reversed: default binding pair is inverted vs. native scroll direction

Device: MX Master 4 (Bolt receiver) · OS: macOS 15.7.9 · Version: v0.6.27 (official cask)

Summary

On the MX Master 4, the thumb wheel's native (undiverted) scroll direction is up-rotation → scroll left, down-rotation → scroll right. OpenLogi's default binding pair says the opposite:

https://github.com/AprilNEA/OpenLogi/blob/v0.6.27/crates/openlogi-core/src/binding/defaults.rs#L36-L37

ButtonId::ThumbwheelScrollUp => Action::HorizontalScrollRight,
ButtonId::ThumbwheelScrollDown => Action::HorizontalScrollLeft,

Because the wheel is only diverted when something differs from defaults (thumbwheel_armed, watchers/gesture.rs#L100: sensitivity ≠ DEFAULT_THUMBWHEEL_SENSITIVITY or a thumbwheel binding ≠ default, computed in capture_plan.rs#L96), this inversion is invisible in the default state — native scroll is what users feel, and it's fine. But it surfaces as two real bugs:

1. Scroll direction cannot be reversed at all

Swapping the two bindings (ThumbwheelScrollUp = "HorizontalScrollLeft", ThumbwheelScrollDown = "HorizontalScrollRight") is non-default → the wheel is diverted → advance() injects sign from the action (gesture.rs#L474-L484) → up injects Left, down injects Right — which is exactly the native direction. Verified on hardware: the swapped config feels identical to the default config. Meanwhile the mapping that would reverse it (up→Right/down→Left, injected) equals the defaults, so it never diverts and never takes effect. Net: no combination of scroll bindings changes the felt direction, and the GUI (correctly, given the model) exposes no reverse option.

2. Moving the sensitivity slider silently flips scroll direction

Changing thumbwheel_sensitivity off 14 — with untouched default bindings — arms the divert by itself, switching the user from native (up→left) to injected defaults (up→right). A user who only wanted faster/slower scrolling gets their horizontal scroll direction reversed as a side effect.

Repro

1. MX Master 4, default config: rotate thumb wheel up → content scrolls left (native).
2. Set only thumbwheel_sensitivity = 15, restart agent: rotate up → content scrolls right (bug 2).
3. Set bindings Up→HorizontalScrollLeft / Down→HorizontalScrollRight (the "swap"): rotate up → content scrolls left — same as step 1, no reversal possible (bug 1).

Proposed fix

Swap the two defaults in defaults.rs:

ButtonId::ThumbwheelScrollUp => Action::HorizontalScrollLeft,
ButtonId::ThumbwheelScrollDown => Action::HorizontalScrollRight,

(+ the GUI's default pair and affected tests, + the doc comment above the defaults.) Then:

• injected-default matches native → sensitivity changes no longer flip direction;
• the binding swap becomes non-default → diverts → genuinely reverses, giving users a working (if TOML-only) reverse today;
• a GUI "reverse direction" toggle becomes a trivial follow-up (it just writes the swapped pair).

Caveats worth a maintainer call: I've verified the native direction on one device (MX Master 4 via Bolt, macOS — the injected CGEvent and native scroll both pass through the same system scroll-inversion handling, so macOS "natural scrolling" doesn't affect the relative comparison). If other thumb-wheel devices share the firmware convention this is universal; and existing configs that explicitly wrote the old default pair would start diverting after the swap (behavior-preserving direction-wise, but they lose native-scroll latency — may warrant a migration touch).

Happy to send the PR if the direction (pun intended) looks right to you.

Workaround for anyone hitting this now: keep the default bindings and set thumbwheel_sensitivity to 15 (forces the diverted path, whose defaults are the reverse of native; ~5% faster than 14, imperceptible).

[linear-code]

OLG-214

[souvlakeeb]

+1 on MX Master 3S.

Was about to write an issue requesting the ability to invert horizontal and vertical scroll separately. Right now, horizontal scroll cannot be changed and seems unaffected by the vertical scroll inversion toggle.

[chrisgleissner]

Same here on MX Master 3S.

I am used to clock-wise movements of the horizontal wheel moving text from left to right. However, it does the opposite, and there is no way to adjust it, unlike with Logitech's own control application.

Version 0.7.1 on Linux (Deb file, Kubuntu 24.04).

This is an absolutely amazing new application btw. Thanks a lot to everyone who contributed!

[Digitalpeer1]

I have the same issue as @souvlakeeb on Fedora the vertical scroll is inverted.

[souvlakeeb]

Hey, @Digitalpeer1, that's not the issue I am having. If you just need to invert vertical scroll, that can be done in the settings, as-is. My issue is there is no way to invert the horizontal scroll at all. And, I would like to be able to invert it separately from the vertical scroll to get my desired behavior. Right now, horizontal scroll direction stays fixed and is not affected by the invert settings.

[cbrenberg]

Same behaviors on MX Master 2S on Windows 11, except that the thumbwheel sensitivity workaround makes no impact on scroll direction behavior.

[DF315000]

MX Master 2S 也有这个需求。
我目前使用 OpenLogi 管理 MX Master 2S，希望能够单独反转**拇指滚轮（横向滚动）**的方向，但目前似乎没有对应的设置。
希望后续可以增加一个类似 “反转拇指滚轮方向” 的独立选项。
设备：Logitech MX Master 2S
系统：Windows 11 专业版 25H2（26200.9168）
连接方式：蓝牙
OpenLogi 版本：0.7.4
如果需要的话，我也可以在 MX Master 2S 上协助测试相关修改。

MX Master 2S has the same need.

I'm currently using OpenLogi with an MX Master 2S, and I would like to be able to reverse the direction of the thumb wheel (horizontal scrolling) independently, but there does not seem to be a corresponding setting at the moment.

It would be great if a separate option such as "Reverse thumb wheel direction" could be added in the future.

Device: Logitech MX Master 2S
OS: Windows 11 Pro 25H2 (26200.9168)
Connection: Bluetooth
OpenLogi version: 0.7.4

If needed, I'd also be happy to help test any related changes on the MX Master 2S.