[pointerevents] May the state of modifier keys influence MouseEvent.button? (#608)

jfirebaugh has just created a new issue for https://github.com/w3c/pointerevents:

== May the state of modifier keys influence MouseEvent.button? ==
Consider:

```
window.document.addEventListener('mousedown', e => console.log(e.button));
```

On the Mac, with default system settings for modifier keys, depressing the primary mouse button with the control key simultaneously depressed produces output that varies between browsers:

* Chrome and Safari produce `0`
* Firefox produces `2`

Does the spec have an opinion on which behavior is correct, or is this left as unspecified platform-dependent/browser-dependent behavior?

Please view or discuss this issue at https://github.com/w3c/pointerevents/issues/608 using your GitHub account


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Received on Monday, 12 January 2026 22:04:18 UTC