271694 2024-03-26 00:07:07 -0700 MouseEvent offsetX and offsetY should be relative to padding edge 2026-01-12 11:06:58 -0800 1 1 1 Unclassified WebKit UI Events Other Unspecified Unspecified RESOLVED FIXED https://bugs.webkit.org/show_bug.cgi?id=218117 InRadar P2 Normal --- 1 mail ahmad.saleem792 ahmad.saleem792 karlcow rniwa simon.fraser webkit-bug-importer oldest_to_newest 2023862 0 470601 mail 2024-03-26 00:07:07 -0700 Created attachment 470601 Demo showing mouse offset coordinates from MouseMove on an element with a thick border. Observed in Epiphany 45.3 on Arch Linux. MouseEvent events include offsetX and offsetY values which should be relative to the border box of the event target (see spec: https://drafts.csswg.org/cssom-view/#dom-mouseevent-offsetx). In WebKit, however, offsetX/Y coordinates appear to be relative to the border box. The attached demo page shows the clientX/Y values when the mouse is moved over a div. When moving the mouse over the thick black border, negative values should be shown (see Firefox and Chromium for correct examples) however positive values are shown instead in WebKit. NB: this appears to be similar (but different) to bug #218117 (MouseEvent.offsetX/Y returns wrong value for inline elements) since this issue relates to block elements and it seems coordinates come relative to the border box, not the padding box. 2023935 1 ap 2024-03-26 08:51:33 -0700 Reproduces in Safari too 2025319 2 webkit-bug-importer 2024-04-02 00:08:13 -0700 <rdar://problem/125763807> 2025649 3 ahmad.saleem792 2024-04-03 03:49:51 -0700 Our implementation: https://searchfox.org/wubkat/rev/2f857be7d42f00feb7b59870709310154181a774/Source/WebCore/dom/MouseRelatedEvent.cpp#183 Blink: https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/events/mouse_event.cc;l=452;drc=2827c7359e94610318802bff2cd4e4d8256cd215 2170504 4 ahmad.saleem792 2026-01-08 18:19:09 -0800 Pull request: https://github.com/WebKit/WebKit/pull/56304 2171244 5 ews-feeder 2026-01-12 11:06:55 -0800 Committed 305479@main (2a4ece3e4b02): <https://commits.webkit.org/305479@main> Reviewed commits have been landed. Closing PR #56304 and removing active labels. 470601 2024-03-26 00:07:07 -0700 2024-03-26 00:07:07 -0700 Demo showing mouse offset coordinates from MouseMove on an element with a thick border. demo.html text/html 325 mail PHN0eWxlPgogICN0YXJnZXQgewogICAgd2lkdGg6IDMwMHB4OwogICAgaGVpZ2h0OiAzMDBweDsK ICAgIAogICAgYm9yZGVyOiAyMHB4IHNvbGlkIGJsYWNrOwogICAgbWFyZ2luOiA0MHB4OwogICAg cGFkZGluZzogNDBweDsKICB9Cjwvc3R5bGU+Cgo8ZGl2IGlkPSJ0YXJnZXQiPjwvZGl2PgoKPHNj cmlwdD4KICBkb2N1bWVudC5nZXRFbGVtZW50QnlJZCgidGFyZ2V0IikuYWRkRXZlbnRMaXN0ZW5l cigibW91c2Vtb3ZlIiwgZXZ0ID0+IHsKICAgIHRhcmdldC5pbm5lclRleHQgPSBgJHtldnQub2Zm c2V0WH0sICR7ZXZ0Lm9mZnNldFl9YDsKICB9KTsKPC9zY3JpcHQ+Cg==