1837973 - `mousedown` button events for Control + left-mouse-button is not aligned with buttons property on Mac

Status: RESOLVED DUPLICATE of bug 1504210

(Core :: DOM: UI Events & Focus Handling, defect)

Description

[fabian.schwarzkopf]

Steps to reproduce:

Similar as reported in https://bugzilla.mozilla.org/show_bug.cgi?id=1615732 and https://bugzilla.mozilla.org/show_bug.cgi?id=1640139. Both are resolved, but the issue is still there.

Reproduce:
Open https://jsfiddle.net/7d4r61p8/1/, press and hold the control button and click the left mouse button.

Actual results:

Firefox shows mousedown, evt.button=2, evt.buttons=1, ctrlKey=true.

Expected results:

All other browsers (Safari, Chrome, Edge) show mousedown, evt.button=0, evt.buttons=1, ctrlKey=true.

Note how the mousedown with ctrl event in Firefox reports "evt.button" === secondary and "evt.buttons" === primary.
So basically a down event whose properties do not line up with each other in the same event.
Ideally, it should resemble the same evt.button and evt.buttons state as the other browsers (i.e. primary for both properties).

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::DOM: UI Events & Focus Handling' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[fabian.schwarzkopf]

Analog for mouseup, it should report "evt.button" === primary then

Comment 3

[Edgar Chen [:edgar]]

The fix is only enabled on Nightly so far, you can flip dom.event.treat_ctrl_click_as_right_click.disabled to enable it on release as workaround.