Module scroll 

Retained scroll state: offsets keyed by widget Key, surviving the per-frame tree rebuild. The layout pass clamps each offset to the current content overflow, so state stays valid as content changes — and, at the same moment, records the geometry it clamped against, which is the only copy of it that outlives the frame (Core::scroll_geometry).

Structs

ScrollGeometry

What the last layout resolved for a scroll container: where the container landed, how big its content came out, and the offset it clamped. All logical px, in the same viewport coordinates on_layout reports.

ScrollStore

Constants

MAX_UNDECLARED_SCROLLS

How many undeclared scroll entries the store keeps before the longest undeclared one is dropped (backlog F26). An entry a layout resolved in the frame that just ended is never evicted, however many there are.