Bug 109230 – REGRESSION(r130089): Scrollbar thumb no longer re-rendered on hover

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Mihai Parparita]

Test case: http://persistent.info/chromium/test-cases/scrollbar-hover.html

If you hover over the main indicated div, its contents turn green. However, the scrollbar thumb (styled via a #scrollable:hover::-webkit-scrollbar-thumb rule) stays red, instead of also turning green (the thumb only changes color when it itself is hovered over).

This used to work as expected before r130089 (is also the behavior seen in Safari 6.0.2 and Chrome 23).

[Alexey Proskuryakov]

Dimitry, do you plan to look into this? Or can r130089 be rolled out?

[Alexey Proskuryakov]

Rolling out seems unlikely, given how old this revision is.

[Dimitri Glazkov (Google)]

Yikes. I totally missed this somehow. I am not planning to tackle this soon.

[Alexey Proskuryakov]

<rdar://problem/13204864>

[Dimitri Glazkov (Google)]

Nils, is this something you might be interested in looking into?

[Nils Barth]

(In reply to comment #5)
> Nils, is this something you might be interested in looking into?

Sure, I can take a look at it!

[Nils Barth]

To add some links; apparently:
r130089: <http://trac.webkit.org/changeset/130089>
which applied Patch 166548 to fix Bug 97953 - Kill transitive effects of SelectorChecker::checkOneSelector.
https://bugs.webkit.org/attachment.cgi?id=166548&action=review
caused this regression.

[Dimitri Glazkov (Google)]

(In reply to comment #7)
> To add some links; apparently:
> r130089: <http://trac.webkit.org/changeset/130089>
> which applied Patch 166548 to fix Bug 97953 - Kill transitive effects of SelectorChecker::checkOneSelector.
> https://bugs.webkit.org/attachment.cgi?id=166548&action=review
> caused this regression.

http://www.youtube.com/watch?v=Ya2xifdO_l0 :-\

[Dimitri Glazkov (Google)]

I didn't realize I caused this. I'll look into this tonight.

[Nils Barth]

Created attachment 189752 [details]
Test case (interactive)

Uploading Mihai's test case for reference.

[Nils Barth]

Created attachment 189754 [details]
Cleanup reftest

[Nils Barth]

Comment on attachment 189752 [details]
Test case (interactive)

Original manual test obsoleted by reftest.

[Nils Barth]

Created attachment 189757 [details]
Test case (interactive) (actual file)

Original test case (for reference; including actual document, not just URL -- oops!)

[Nils Barth]

Comment on attachment 189757 [details]
Test case (interactive) (actual file)

Obsoleted by reftest

[Nils Barth]

Created attachment 189761 [details]
Update reftest: also style scrollbar itself

[Nils Barth]

Just uploaded a reftest.

Looked into this a bit -- as Mihai notes, this looks to be a *re-rendering* issue.
Hover correctly updates the CSS (per DOM Inspector), but the scrollbar thumb pseudo-element isn't re-rendered.
This also affects the scrollbar (background) itself; it's not something special to the thumb.

Dimitri, as you wrote the patch fixing the earlier bug, you're naturally best-placed to address this, but if you'd like me to look into it further I'd be happy to.
(Writing the reftest didn't require understanding what's going on under the hood, so that was easy enough.)

[Dimitri Glazkov (Google)]

(In reply to comment #16)
> Just uploaded a reftest.

Bless you. A true Barth.

[Dimitri Glazkov (Google)]

This looks promising.

[Dimitri Glazkov (Google)]

Created attachment 189832 [details]
Patch

[Eric Seidel (no email)]

Comment on attachment 189832 [details]
Patch

er mer gerd

[WebKit Review Bot]

Comment on attachment 189832 [details]
Patch

Clearing flags on attachment: 189832

Committed r143819: <http://trac.webkit.org/changeset/143819>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.