Read-only view of every node currently attached to this manager,
in attachment order. FocusTraversalGroup uses this to find
candidates for directional focus.
Whether the focused node claims typed text (a focused, editable
TextInput). While true, chords shadowed by text input
(KeySequence.isShadowedByTextInput) can never fire — the claimant
consumes the characters before chord matching runs. The hint bar uses
this to hide such bindings instead of advertising dead keys.
Marks this notifier as disposed and drops its listeners. Nulls the slots
in place (rather than replacing the backing list) so a dispose called
from within a listener leaves any in-progress notify walk
reading valid, now-empty slots. After disposal, addListener and
notify throw; removeListener remains safe for cleanup.
Moves focus to the next focusable node in reading order
(top-to-bottom, then left-to-right), cycling at the end. Skips
nodes that can't take focus or are flagged skipTraversal. Returns
whether focus moved. This is the mechanism behind Tab traversal;
the key bindings live in FocusTraversalGroup.
Whether node is currently traversable: it can take focus, isn't
flagged skipTraversal, and sits under no active ExcludeFocus.
Both the Tab and the arrow-key policies consult this.
Lifts the outermost active ExcludeFocus marker(s) inside root,
ahead of the rebuild that will flip them off. For containers that
reveal previously covered content by intent (Navigator.pop wraps each
route in ExcludeFocus(excluding: !isTop)): the reveal is decided
NOW, but the marker widget only updates next frame — lifting eagerly
lets focus restoration run synchronously and lets app code claim
focus into the revealed subtree from completion microtasks. The walk
never descends past a marker, so an app's own nested ExcludeFocus
(a hidden tab, say) stays excluded; each lifted marker re-syncs to
its widget configuration on its next update.
Called by KeyBindings when its binding list changes in place (a
rebuild produced a new list — new labels, enabled flags, or chords)
without any focus movement. Notifies manager listeners (the hint bar
depends on the manager) so they repaint against the new bindings. On a
microtask — this is invoked from didUpdateWidget, mid-build, where a
synchronous notify would re-enter setState on a dependent.
Releases the nearest trapping FocusScope enclosing context
immediately, ahead of the rebuild that will flip its trapFocus flag
off or remove the scope.
Restores focus to the node most recently focused within the nearest
FocusScope enclosing context (the scope's focus memory). Returns
whether focus moved.
