1881940 - Enabling layout.css.modern-range-pseudos.enabled breaks Rules view

Status: VERIFIED FIXED

(DevTools :: Inspector, defect, P2)

Description

[Joe T]

Attachment: CSS inspector broken - cannot edit active style rules

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:124.0) Gecko/20100101 Firefox/124.0

Steps to reproduce:

• Enable "layout.css.modern-range-pseudos.enabled" in about:config
• Restart Firefox
• Open Dev Tools on any website

Actual results:

While disabled, the CSS inspector/editor works just fine: you can see active rules and make live changes.

After enabling the setting, the CSS inspector is blank. You can't see/edit active rules or add new ones. You can view Layout, Computed, etc. but can't make changes.

---

i attempted troubleshooting mode (no extensions) and it didn't have any impact on the setting. Only when i tested a new clean profile and the behavior wasn't there, i started tinkering with prefs.js and tracked it down.

Expected results:

i don't know what this preference is for, so i can't speak to what change it should have in website behavior, but i don't think a preference altering CSS behavior should impact the Dev Tools. The tools may not support whatever CSS alteration occurs, but the UI shouldn't break because of it.

Comment 1

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

The Bugbug bot thinks this bug should belong to the 'DevTools::Inspector' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Nicolas Chevobbe [:nchevobbe]]

This is probably because of the slider-* pseudo-elements, I'll have a look

Comment 3

[Nicolas Chevobbe [:nchevobbe]]

Attachment: Bug 1881940 - [devtools] Display ::slider-* pseudo elements in Rules view. r=#devtools-reviewers.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/6a54dc1a6d89
[devtools] Display ::slider-* pseudo elements in Rules view. r=devtools-reviewers,ochameau.

Comment 5

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/6a54dc1a6d89

Comment 6

[Ardelean Oana, Desktop Test Engineering [:oardelean]]

Reproducible on a 2024-02-24 Nightly build on macOS 12.
Verified as fixed on Firefox Nightly 126.0a1 and Firefox 125.0b4 on macOS 12, Windows 10, Ubuntu 22.