Bug 215664

Summary: [macOS] Web pages are not responding correctly to changes in "Reduce motion" setting
Product: WebKit Reporter: Per Arne Vollan <pvollan>
Component: WebKit Misc.Assignee: Per Arne Vollan <pvollan>
Status: RESOLVED FIXED    
Severity: Normal CC: bfulgham, darin, simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
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Description Per Arne Vollan 2020-08-19 14:47:52 PDT 
Web pages are not responding correctly to changes in the "Reduce motion" accessibility setting under System Preferences > Accessibility > Display. This can for example be seen on https://webkit.org/blog-files/prefers-reduced-motion/prm.htm, while changing the setting.
Comment 1 Per Arne Vollan 2020-08-19 14:59:21 PDT 
Created attachment 406875 [details]
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Comment 2 Per Arne Vollan 2020-08-19 15:51:58 PDT 
Created attachment 406880 [details]
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Comment 3 Per Arne Vollan 2020-08-19 15:52:46 PDT 
<rdar://problem/66343795>
Comment 4 Darin Adler 2020-08-19 16:17:26 PDT 
Comment on attachment 406880 [details]
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View in context: https://bugs.webkit.org/attachment.cgi?id=406880&action=review

> Source/WebKit/ChangeLog:3
> +        [macOS] Web pages are not responding correctly to changes in "Reduce motion" setting

How did we happen to overlook this one but not others? Are there any more of these?
Comment 5 Per Arne Vollan 2020-08-19 16:43:28 PDT 
(In reply to Darin Adler from comment #4)
> Comment on attachment 406880 [details]
> Patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=406880&action=review
> 
> > Source/WebKit/ChangeLog:3
> > +        [macOS] Web pages are not responding correctly to changes in "Reduce motion" setting
> 
> How did we happen to overlook this one but not others? Are there any more of
> these?

Yes, there are potentially more of these cases, since this race is a general issue when updating preferences from the UI process, where the race is usually won by the notification. It might be possible to solve this in a more general way, but I have not been able to think of a way to do that so far. I will try to think of a more general solution.

Thanks for reviewing!
Comment 6 Per Arne Vollan 2020-08-20 07:31:42 PDT 
Created attachment 406930 [details]
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Comment 7 Per Arne Vollan 2020-08-20 08:08:17 PDT 
Created attachment 406931 [details]
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Comment 8 Per Arne Vollan 2020-08-20 08:58:07 PDT 
Created attachment 406935 [details]
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Comment 9 Per Arne Vollan 2020-08-20 09:06:40 PDT 
The new API test is succeeding locally, but failing on the bots.
Comment 10 Per Arne Vollan 2020-08-20 09:30:09 PDT 
Created attachment 406937 [details]
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Comment 11 Per Arne Vollan 2020-08-20 12:13:57 PDT 
Created attachment 406953 [details]
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Comment 12 Per Arne Vollan 2020-08-20 12:40:16 PDT 
Created attachment 406955 [details]
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Comment 13 Per Arne Vollan 2020-08-20 15:31:01 PDT 
Created attachment 406975 [details]
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Comment 14 Per Arne Vollan 2020-08-20 16:48:12 PDT 
Created attachment 406978 [details]
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Comment 15 Per Arne Vollan 2020-08-20 17:21:51 PDT 
Created attachment 406981 [details]
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Comment 16 Per Arne Vollan 2020-08-20 17:51:31 PDT 
Created attachment 406988 [details]
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Comment 17 Per Arne Vollan 2020-08-20 18:37:54 PDT 
Created attachment 406995 [details]
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Comment 18 Per Arne Vollan 2020-08-20 19:03:29 PDT 
Created attachment 406997 [details]
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Comment 19 EWS 2020-08-20 19:31:45 PDT 
Committed r265996: <https://trac.webkit.org/changeset/265996>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 406997 [details].
Comment 20 Simon Fraser (smfr) 2020-08-20 20:23:19 PDT 
How many other preferences are going to suffer from this same bug?
Comment 21 Darin Adler 2020-08-21 09:16:53 PDT 
I asked the same question and the answer is in comment #5.