A hidden frame resolved and fired `OnSizeChanged` at once, a getter's resize fired at the drain, and `GetWidth`/`GetHeight` answered the rect over scale.
In 1.12.1 hiding sets the deferral flag `0x2` (`0x76ad50`); while set, an invalidate marks the frame pending and passes it to its dependents without a resolve (`0x768178`). Show resolves it first (`0x76ae58`), a getter resolves a pending one and fires `OnSizeChanged` inside the read (`0x7a1980`, `0x76b580`), and an anchor read pulls it for good (`0x7a2fc0`). `GetWidth` answers the set size when non-zero, else the rect span, unscaled (`0x7a1e93`, `0x7a1ee6`).
The deferral is modelled for frames and regions, getters fire inside the read, layout ids mint in handle order (deterministic), and the options window measures its scroll by its edges.
Tests bite on the parent; the verifier is green; stock quads match.
Fixes#948Fixes#971🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
