Fix scroll modifiers getting stuck when TouchPhase::End never arrives - #8636
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SulimanAbdulrazzaq wants to merge 1 commit into
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winit on Wayland sends `TouchPhase::Start` for some mouse wheels, but never `TouchPhase::End`. The `WheelState` then stayed `InTouch` forever, where modifiers only accumulate. After a single ctrl+scroll, every later scroll was a zoom, and `is_scrolling()` never went back to `false`. End an `InTouch` scroll action after the same 150 ms without scroll events that we already use for `Smoothing`. Check this both in `after_events` and when the next scroll event arrives, since an idle app may not run a pass after the timeout.
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Preview available at https://egui-pr-preview.github.io/pr/8636-fixwheel-missing-touch-end View snapshot changes at kitdiff |
SulimanAbdulrazzaq
marked this pull request as ready for review
September 25, 2026 15:53
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@emilk when you have a moment, could you take a look at this one? Everything is green on the current head except the |
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winit on Wayland sends
TouchPhase::Startfor some mouse wheels, but neverTouchPhase::End(winit's own comment in its Wayland pointer handler: "theEndedis not guaranteed to be sent for mouse wheels"). Since #7678,WheelStatethen staysInTouchfor good, and inInTouchthe modifiers are only ever added to. So after a single ctrl+scroll, every later scroll is a zoom, which is what #8325 bisected to 1b77d70.is_scrolling()also staystrue, and withshow_tooltips_only_when_stillthat keeps tooltips from showing.This ends an
InTouchscroll action after 150 ms without scroll events, the same timeoutSmoothingalready uses. The check runs inafter_events, and also when the next wheel event arrives, because an idle app may not run a pass after the timeout has passed. While events keep coming, the modifiers stay latched as #7678 intended.Tests, in
wheel_state.rs:modifiers_should_not_stick_when_touch_phase_end_never_arrives:Start+Movewith ctrl, then 1 s later aMovewithout ctrl. Before the fix it zoomed (left: 0.9753099,right: 1.0).scroll_action_should_end_when_touch_phase_end_never_arrives:is_scrolling()isfalseafter a second without scroll events. Before the fix it stayedtrue.modifiers_should_stick_until_touch_phase_end: letting go of shift mid-scroll still scrolls horizontally untilEnd(the Improve modifier handling when scrolling #7678 behavior). Passes before and after.cargo test -p egui --all-featurespasses (75 unit tests, 186 doc-tests), and so docargo fmt,./scripts/lint.py,cargo clippy -p egui --all-features --all-targets -- -D warningsandcargo doc -p egui --document-private-items. The whole-workspacecargo test --all-featureson macOS (with the snapshot tests) passes too. I don't have a niri or COSMIC setup, so the tests replay winit's event sequence rather than a real wheel.