304726 2025-12-27 05:16:07 -0800 REGRESSION (Safari 26.2): Scrollbar drag fails on first attempt after dynamic DOM replacement in overflow container 2026-01-09 15:08:51 -0800 1 1 1 Unclassified WebKit Scrolling Safari 26 Mac (Apple Silicon) macOS 26 RESOLVED FIXED InRadar P2 Normal --- 1 kchs29 simon.fraser simon.fraser webkit-bug-importer oldest_to_newest 2168336 0 477858 kchs29 2025-12-27 05:16:07 -0800 Created attachment 477858 Minimal test case to reproduce the bug ## Problem Scrollbar drag completely fails on first attempt after dynamic DOM replacement inside an overflow container. The thumb does not move at all. Second attempt works normally. Mouse wheel scrolling always works. Both vertical and horizontal scrollbars are affected. ## Steps to Reproduce 1. Create a container with overflow: scroll (or overflow-x/overflow-y) 2. Replace inner DOM content via JavaScript (e.g., innerHTML) 3. Immediately try to drag the scrollbar thumb ## Expected Scrollbar drag works on first attempt. ## Actual First drag fails (thumb doesn't move at all). Second drag works. ## Regression - Safari 26.1 (21622.2.11.11.9): Works correctly ✅ - Safari 26.2 (21623.1.14.11.9): Bug occurs ❌ ## Test Case See attached: webkit-bug-testcase.html 2168385 1 webkit-bug-importer 2025-12-27 21:02:35 -0800 <rdar://problem/167249048> 2170158 2 simon.fraser 2026-01-07 18:46:43 -0800 I can reproduce even on first load of the attachment. 2170175 3 simon.fraser 2026-01-07 21:40:28 -0800 Pull request: https://github.com/WebKit/WebKit/pull/56239 2170780 4 ews-feeder 2026-01-09 15:08:49 -0800 Committed 305383@main (bc68ba9c807c): <https://commits.webkit.org/305383@main> Reviewed commits have been landed. Closing PR #56239 and removing active labels. 477858 2025-12-27 05:16:07 -0800 2025-12-27 05:16:07 -0800 Minimal test case to reproduce the bug webkit-bug-testcase.html text/html 5497 kchs29 PCFET0NUWVBFIGh0bWw+CjxodG1sIGxhbmc9ImVuIj4KPGhlYWQ+CiAgPG1ldGEgY2hhcnNldD0i VVRGLTgiPgogIDxtZXRhIG5hbWU9InZpZXdwb3J0IiBjb250ZW50PSJ3aWR0aD1kZXZpY2Utd2lk dGgsIGluaXRpYWwtc2NhbGU9MS4wIj4KICA8dGl0bGU+V2ViS2l0IEJ1ZyBUZXN0OiBTY3JvbGxi YXIgRHJhZyBGYWlscyBBZnRlciBET00gUmVwbGFjZW1lbnQ8L3RpdGxlPgogIDxzdHlsZT4KICAg ICogewogICAgICBib3gtc2l6aW5nOiBib3JkZXItYm94OwogICAgfQogICAgYm9keSB7CiAgICAg IGZvbnQtZmFtaWx5OiAtYXBwbGUtc3lzdGVtLCBCbGlua01hY1N5c3RlbUZvbnQsIHNhbnMtc2Vy aWY7CiAgICAgIHBhZGRpbmc6IDIwcHg7CiAgICAgIG1heC13aWR0aDogODAwcHg7CiAgICAgIG1h cmdpbjogMCBhdXRvOwogICAgfQogICAgaDEgewogICAgICBmb250LXNpemU6IDE4cHg7CiAgICAg IG1hcmdpbi1ib3R0b206IDEwcHg7CiAgICB9CiAgICAuaW5zdHJ1Y3Rpb25zIHsKICAgICAgYmFj a2dyb3VuZDogI2Y1ZjVmNTsKICAgICAgcGFkZGluZzogMTVweDsKICAgICAgYm9yZGVyLXJhZGl1 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