User request: the toolbar frame resizes vertically between one row (row 2
hidden, minimum) and two rows (shown), SNAPPING between the two stops; default
expanded. Small toolkit feature: UiElement.MaxHeight + a ResizableEdges mask
(bottom-edge-only) + a UiCollapsibleFrame (snaps height to the nearer stop and
ties row-2 visibility to it in OnTick) + the GameWindow mount (compute the two
heights from the layout, top-anchor the content so row 1 never reflows). Retail's
real mechanism is keystone.dll (no decomp) + the dat stacks both rows always —
so this is a toolkit UX from the user's retail observation; amends IA-17.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
