FA-39564 / Tree accessibility / Member archive
Expanded tree viewport anchor stabilization: Anchor relative offset is reused for a replacement row · case 04
Anchor relative offset is reused for a replacement row produces the wrong hierarchical widget state in a regression fixture.
Case contract
After branch expansion changes row heights/order, preserve the first visible surviving anchor and its pixel offset. If that row is removed, use the next surviving old row, then previous row. Clamp scroll to content extent, include fractional row offsets, and keep active-row identity independent from viewport anchoring.
Why this case matters
Offline executable model of a hierarchical accessibility interaction; inputs are bounded and valid as stipulated. No browser, assistive technology, or normative ARIA conformance is claimed.
One recorded failure
Sample boundary fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| oversized offset | ["b", 86, 106, "a"] | ["b", 82, 106, "a"] | Failed |
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