Interaction · Keys, scroll and focus: roving focus, scroll sync, type-ahead

RovingFocus keeps a row or column of items behind one Tab stop: the
arrows walk focus, Home and End reach the ends, Enter or Space presses,
and a press moves the stop without taking focus. ScrollSync keeps boxes
at one place along an axis: the pane a wheel turned leads, and a canvas
ahead of the panes copies its place before they draw. SelectableList
moves its cursor to the row that starts with the letters typed, the
letters joining within a pause and a Command letter left to the app.
forms::History becomes public as the undo manager. The gallery shows
gpui's own key bindings, a two-stroke chord waiting on its first
stroke, uniform_list, autofocus and the focus ring.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tasks/ch31-43.md

@@ -235,16 +235,16 @@
 
 ## T38b Interaction · Keys, scroll and focus
 
-- [ ] Hotkeys / KeyBinding — native `actions!`, `bind_keys`, `key_context`
-- [ ] KeyChord — native multi-keystroke bindings
-- [ ] Undo / Redo Manager
-- [ ] InfiniteScroll Trigger → `lists::InfiniteList`
-- [ ] VirtualScroller — native `list()` / `uniform_list()`
-- [ ] ScrollSync
-- [ ] Autofocus — native `window.focus()`
-- [ ] RovingTabIndex
-- [ ] TypeAhead
-- [ ] FocusVisible → `primitives::FocusRing`
+- [x] Hotkeys / KeyBinding — native `actions!`, `bind_keys`, `key_context`
+- [x] KeyChord — native multi-keystroke bindings; `window.pending_input_keystrokes()` shows the first stroke
+- [x] Undo / Redo Manager → `forms::History`, made public
+- [x] InfiniteScroll Trigger → `lists::InfiniteList`
+- [x] VirtualScroller — native `list()` / `uniform_list()`
+- [x] ScrollSync
+- [x] Autofocus — native `window.focus()`
+- [x] RovingTabIndex → `interaction::RovingFocus`
+- [x] TypeAhead → `lists::SelectableList`, whose letters move its cursor
+- [x] FocusVisible → `primitives::FocusRing`
 
 ## T39 Theme — `src/theme`