RESOLVED FIXED313543
Always-on scrollbars are invisible when on root element of nested documents 
https://bugs.webkit.org/show_bug.cgi?id=313543
Summary Always-on scrollbars are invisible when on root element of nested documents
oss
Reported 2026-04-28 07:29:42 PDT
Created attachment 479353 [details] iframe vs normal div scrollbar rendering When a nested documents scrollingElement (html) is configured as a scroll container w/ "display: flex", its scrollbar thumb is not rendered. See attachment for test/reproduction, which both Gecko and Blink pass.
Attachments
iframe vs normal div scrollbar rendering (6.89 KB, text/html)
2026-04-28 07:29 PDT, oss 		no flags
Details
Test reduction (289 bytes, text/html)
2026-04-28 08:00 PDT, alan 		no flags
Details
Patch (4.30 KB, patch)
2026-04-28 09:24 PDT, alan 		no flags
DetailsFormatted DiffDiff
Patch (4.32 KB, patch)
2026-04-28 10:48 PDT, alan 		no flags
DetailsFormatted DiffDiff
Patch (4.73 KB, patch)
2026-04-28 17:07 PDT, alan 		no flags
DetailsFormatted DiffDiff
[fast-cq]Patch (6.98 KB, patch)
2026-04-29 05:16 PDT, alan 		no flags
DetailsFormatted DiffDiff
Show Obsolete (3) View All Add attachment proposed patch, testcase, etc.
alan
Comment 1 2026-04-28 08:00:54 PDT
Created attachment 479354 [details] Test reduction Thank you for filing this bug report and for the great test cases.
alan
Comment 2 2026-04-28 09:24:50 PDT
Created attachment 479356 [details] Patch
alan
Comment 3 2026-04-28 10:48:09 PDT
Created attachment 479357 [details] Patch
Simon Fraser (smfr)
Comment 4 2026-04-28 11:21:50 PDT
Comment on attachment 479357 [details] Patch Doesn't the test need to disable mock scrollbars?
alan
Comment 5 2026-04-28 17:07:12 PDT
Created attachment 479358 [details] Patch
alan
Comment 6 2026-04-29 05:16:24 PDT
Created attachment 479366 [details] [fast-cq]Patch
EWS
Comment 7 2026-04-29 10:39:07 PDT
Committed 312300@main (91286d4579c9): <https://commits.webkit.org/312300@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 479366 [details].
Radar WebKit Bug Importer
Comment 8 2026-04-29 10:40:14 PDT
<rdar://problem/175866046>
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