311544 2026-04-05 19:04:54 -0700 [WPE][GTK] preventDefault() on pointerdown does not suppress gesture-based compatibility mouse events from touch 2026-04-08 23:31:07 -0700 1 1 1 Unclassified WebKit WPE WebKit WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED P2 Normal --- 1 klee webkit-unassigned bugs-noreply oldest_to_newest 2197136 0 klee 2026-04-05 19:04:54 -0700 On WPE (and likely GTK), calling preventDefault() on a pointerdown event does not suppress compatibility mouse events generated from touch input. After every touch tap, mouse emulation events (pointerId=1, pointerType=mouse) are fired at the same coordinates regardless of whether pointerdown was cancelled. Per the W3C Pointer Events spec (https://w3c.github.io/pointerevents/#compatibility-mapping-with-mouse-events): "Authors can prevent the production of certain compatibility mouse events by canceling the pointerdown event." "Mouse events can only be prevented when the pointer is down. Hovering pointers (e.g. a mouse with no buttons pressed) cannot have their mouse events prevented." - Test case: document.documentElement.addEventListener("pointerdown", (e) => { e.preventDefault(); }, true); - How to reproduce: 1. Create a page with a pointerdown handler that calls e.preventDefault() 2. Load it in WPE browser with touch input 3. Tap the screen - Expected Result: - pointerdown (touch) fires, app calls preventDefault() - No compatibility mouse events should follow - Actual Result: - pointerdown (touch) fires, app calls preventDefault() - pointermove/pointerover with pointerId=1, pointerType=***mouse*** fires ~1ms later 2197138 1 klee 2026-04-05 19:12:04 -0700 Pull request: https://github.com/WebKit/WebKit/pull/62097 2198270 2 ews-feeder 2026-04-08 23:31:04 -0700 Committed 310827@main (45f6219e113d): <https://commits.webkit.org/310827@main> Reviewed commits have been landed. Closing PR #62097 and removing active labels.