1392446 - Stylo: Rules Inspector Empty

Status: RESOLVED DUPLICATE of bug 1390455

(DevTools :: Inspector: Rules, defect)

Description

[Stephanie Hobson [:shobson]]

Attachment: Screen Shot 2017-08-21 at 16.26.32.png

The rules inspector periodically goes empty.

Things that do not fix it:
- trying to inspect a different element
- switching to the Layout Inspector and back
- closing dev tools and re opening them
- opening the same webpage in a new tab and and trying to inspect it there

Browser console output:

<unavailable>  protocol.js:938
Protocol error (unknownError): couldn't find start of the rule  utils.js:207
Protocol error (unknownError): couldn't find start of the rule  rules.js:821
<unavailable>  protocol.js:938
Protocol error (unknownError): couldn't find start of the rule  utils.js:207
Protocol error (unknownError): couldn't find start of the rule  rules.js:821
<unavailable>  protocol.js:938
Protocol error (unknownError): couldn't find start of the rule  utils.js:207
Protocol error (unknownError): couldn't find start of the rule  rules.js:821

Comment 1

[Stephanie Hobson [:shobson]]

PS, I am on 57.0a1

Comment 2

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

Does the issue go away if you disable Stylo in about:config (layout.css.servo.enabled to false)?

Comment 3

[Stephanie Hobson [:shobson]]

I had been working on the page for some time before the problem started the first time.

I disabled Stylo, opened and closed the dev tools, and it did not go away. But then I closed the dev tools and refreshed the page and re-opened dev tools and it was fixed. 

This was happening to me last week too, not sure when Stylo was switched on.

Comment 4

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

The is currently an active experiment for Stylo in Nightly, with 80% on / 20% off, so that might be why you've seen different things over time.

You do need to reload the page to apply the pref change, so what you described sounds like a Stylo issue.

Can you share the CSS file for those elements?  I'd like to figure out of it's related to bug 1390455, which is about non-ASCII characters in the CSS file.

Comment 5

[Stephanie Hobson [:shobson]]

I think it was this page: https://developer.mozilla.org/pt-BR/docs/Glossario/Grid_Areas$edit

You will have to create an account to see the page if you don't have one already.

Comment 6

[Stephanie Hobson [:shobson]]

Files should not need a login:

https://developer.cdn.mozilla.net/static/build/styles/mdn.e1f2a23178fe.css
https://developer.cdn.mozilla.net/static/build/styles/wiki.ef66c14452d5.css
https://developer.cdn.mozilla.net/static/build/styles/wiki-edit.6355730f8a57.css
https://developer.cdn.mozilla.net/static/build/styles/jquery-ui.416bba5cbf7d.css
https://developer.cdn.mozilla.net/static/build/styles/editor-content.12299101314d.css

It was definitely an edit page (this time), and all the editing pages include the same .css files so even if I have the wrong page those are likely the right .css files.

Comment 7

[Gabriel Luong [:gl] (ΦωΦ)]

Thanks for the report Stephanie!

Does the markup/dom view go empty at all or is it just the rule view?

Comment 8

[Safwan Rahman (:safwan)]

I think duplicate of bug 1390455

Comment 9

[Stephanie Hobson [:shobson]]

Just the rule view (see screen shot with comment 0)

Happened again here: https://developer.mozilla.org/en-US/ You don't need to login for that one ;)

First time it has happened to me immediately upon opening the tools in a new tab on a new page.

Comment 10

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

Okay, I just tried out https://developer.mozilla.org/en-US/ and I can verify the issue.  It seems like it's related to Font Awesome, which uses non-ASCII rules like:

.icon-music:before {
 content:""
}

So, seems like it is indeed the same as bug 1390455.  Thanks for filing, we'll track it over there!

Comment 11

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

Ah, just thought I should add that using the Style Editor to remove all these non-ASCII things makes the rule view work again, so that's why I feel confident it's the same.