1600773 - there is no cursor hover feedback for tab bar scroll buttons

Status: VERIFIED FIXED

(Core :: CSS Parsing and Computation, defect, P2)

Description

[Will]

Attachment: tbsabhf.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:72.0) Gecko/20100101 Firefox/72.0

Steps to reproduce:

Open tabs until the scroll buttons appear in the tab bar. Now hover the cursor over the scroll arrows and observe there is no hover feedback. There should be hover feedback for the tab bar scroll buttons. Repro'd in Nightly 72.0a1 (2019-12-02) as well as Beta 71.0 (see attached screenshot, red arrows pointing to the buttons that have no hover feedback)

Comment 1

[Gingerbread Man]

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:72.0) Gecko/20100101 Firefox/72.0
20191202091209

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=94eaa02e0ea1725512893cd5139b1d200fcf4fdd&tochange=5e221240fc1d537da612973800bbe24efa50736b

Comment 2

[Brian Grinstead [:bgrins]]

Emilio, should these two :hover rules be working? https://searchfox.org/mozilla-central/rev/04d8e7629354bab9e6a285183e763410860c5006/browser/themes/shared/toolbarbuttons.inc.css#178-179.

I expect so based on https://drafts.csswg.org/css-shadow-parts/#part:

The shadow-part pseudo-elements can take additional pseudo-classes after them, such as x-button::part(label):hover, but never match the structural pseudo-classes or any other pseudo-classes that match based on tree information rather than local element information.

If I test with a content test case like:

data:text/html,<style>
      my-element::part(inner):hover { background: red; }
    </style>
    <script>
      customElements.define(
        "my-element", class extends HTMLElement {
          constructor() {
            super();
            this.attachShadow({ mode: "open" });
            this.shadowRoot.innerHTML = "<span part='inner'>a</span>";
          }
        }
      );
    </script>
    <my-element></my-element>

then the hover rule doesn't apply, but if I change the selector to my-element:hover::part(inner) then it does (of course, it's not the desired behavior but it does work just as a sanity check).

Comment 3

[Emilio Cobos Álvarez (:emilio)]

Yes it should, it's a silly bug.

Comment 4

[Emilio Cobos Álvarez (:emilio)]

Attachment: testcase

If you uncomment the rule inside the shadow root, then it works.

Comment 5

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1600773 - Invalidate shadow part pseudo-class styles correctly. r=heycam

I was going to send a test for :focus via wpt, but then realized it was
probably not spec-compliant with the new rules people want to follow for
:focus, so I filed https://github.com/w3c/csswg-drafts/issues/4555 instead.

Testing :hover / :active via wpt looked quite a bit of a hassle.

Comment 6

[Emilio Cobos Álvarez (:emilio)]

BTW, this works on Linux, is this bug mac/win only or something?

Comment 7

[Will]

(In reply to Emilio Cobos Álvarez (:emilio) from comment #6)

BTW, this works on Linux, is this bug mac/win only or something?

my laptop is on Windows 10 v1903, sorry I don't have access to and macs or linux machines

Comment 8

[Brian Grinstead [:bgrins]]

(In reply to Emilio Cobos Álvarez (:emilio) from comment #6)

BTW, this works on Linux, is this bug mac/win only or something?

I can reproduce the reported problem and the reduced cases in Comment 2 / Comment 4 on OSX.

Comment 9

[Alin Ilea, Desktop Test Engineering]

Hi,

This issue is also reproducible on latest Nightly 73.0a1 (2019-12-02), so I will update the flag accordingly.

Comment 10

[Emilio Cobos Álvarez (:emilio)]

Comment on attachment 9113097 [details]
Bug 1600773 - Invalidate shadow part pseudo-class styles correctly. r=heycam

Beta/Release Uplift Approval Request

• User impact if declined: see comment 0
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: comment 0
• List of other uplifts needed: none
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Invalidates ::part() pseudo rules more often.
• String changes made/needed: none

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/dc7693501534
Invalidate shadow part pseudo-class styles correctly. r=heycam

Comment 12

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/dc7693501534

Comment 13

[Alin Ilea, Desktop Test Engineering]

Verified - fixed on latest Nightly 73.0a1 (2019-12-09) (Build id: 20191209215019) on Mac OS 10.14 and Windows 10.

Comment 14

[Julien Cristau [:jcristau]]

Comment on attachment 9113097 [details]
Bug 1600773 - Invalidate shadow part pseudo-class styles correctly. r=heycam

stylo regression introduced in 71. verified in nightly, adds test. approved for 72.0b5

Comment 15

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/releases/mozilla-beta/rev/f41a72eb9c5f

Comment 16

[Alin Ilea, Desktop Test Engineering]

Verified - fixed on latest Beta 72.0b5 (Build id: 20191210160808) on Mac OS 10.14 and Windows 10.