Bound the overlap-offset window scan so an unresponsive app can't freeze the UI - #1810
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MyronKoch wants to merge 1 commit into
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Bound the overlap-offset window scan so an unresponsive app can't freeze the UI#1810MyronKoch wants to merge 1 commit into
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The overlap-offset check enumerates every window over the accessibility API on the main thread before each grid placement. A hung app - or, under heavy system load, a merely sluggish one - can block that enumeration for the full default AX timeout (seconds), freezing the UI on every window move. Set a 0.25s messaging timeout on the system-wide element for the duration of the scan and restore the default right after; an app that can't answer in time is skipped (no offset), which is harmless.
MyronKoch
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When cycling a window onto a grid position, the overlap-offset check (from #1762) enumerates every on-screen window over the Accessibility API to see whether one already sits at the target position — and that scan runs on the main thread before the placement.
Normally that's a few milliseconds. But an Accessibility query to an unresponsive app blocks until the default messaging timeout, which is several seconds. So if any app is hung or beachballing, moving a window can freeze Rectangle's UI for that whole duration, on every placement.
Fix: set a 0.25s AX messaging timeout on the system-wide element for the duration of the scan, and restore the default immediately after via
defer. An app that doesn't answer within the cap is simply skipped (no offset applied for it), which is harmless. Under normal conditions nothing changes — responsive apps answer far faster than the cap.Only affects the overlap-offset path (behind
cyclingOverlapOffset).