Win32: Track popup-host continuation, lifecycle, and accessibility capabilities #4384

Purpose

Track the Office/REX host capabilities needed by the Popover (#4236), Menu (#4232), MenuButton (#4231), and Dropdown (#4224) implementation plan. This is the Win32 host follow-up to #4377 and #4376, not an expansion of the stable native-core /legacy API.

Approved interim

The owner approved the Win32 interim on October 16, 2026: Tab/Shift+Tab close the popup and return to its live trigger instead of continuing past it. All four desktop endpoints still ship together. This exception does not claim owner-relative continuation and must be documented and tested explicitly. Do not synthesize a second Tab or require caller-supplied neighboring targets.

Host capability backlog

• Add owner-relative forward/backward Tab continuation from the trigger's actual native tab position, including native Office controls, disabled/reordered stops, and active-window guards (A1).
• Qualify onShow as attached/positioned readiness and the ordering of setInitialFocus/RCTFocusTrapZone focus events; add a native result or ordering guarantee if the existing host cannot establish them (B1/B2).
• Qualify child-popup input, ancestor input, deepest Escape, sibling replacement, and atomic family closure; add family support where the current host fails (B3/B8).
• Qualify restoration against later focus moves into native Office controls and trigger press-in/light-dismiss/press ordering; add guarded restoration or anchor-aware dismissal if needed (B4/B5).
• Qualify the actual key descriptors honored by the host and native UIA menu/combobox/list selection patterns, states, operations, and cross-window ControllerFor relationships; fix missing transport/projection where needed (B6/B7).
• Consider close/reposition acknowledgements, precise outside/deactivation dismissal causes, and live system menu-show-delay publication as enhancements (C1-C3).

B items are qualification questions, not assertions that the baked host is defective. The current baseline is React Native Win32 0.81.9 / REX 0.81.1. This repository cannot add compiled functionality to that prebuilt host.

Integration contract

• Detect actual view-manager props/events/commands instead of sniffing product versions. Never dispatch a new managed command unless the host declares it.
• Keep unclassified dismissal and unsupported operation results truthful; do not manufacture readiness or confirmation.
• Preserve existing native registration names and /legacy signatures/React compatibility.
• Record the host owner, release vehicle, capability metadata, exact build/integration result, and physical input plus intended UIA-pattern evidence before enabling each addition. Owner/release vehicle remain to be assigned.