A pinned viewport shook during window resizes while a scrolled-up one
stayed calm: both pinning mechanisms — the growth corrections and the
list's maintain-scroll-at-end — re-assert the end against rows that are
still re-measuring, fighting the size compensation that keeps the free
case stable. While the width is actively changing, stand both down and
hold the reading position the same way the free path does, then re-assert
the live edge once with a single instant write after the resize settles
(only when the viewport was still following).
Bohdan Triapitsyn
5c39db0e36