Struct TabBar 

pub struct TabBar {
    pub pending_drag: Option<DragPayload>,
    pub pending_reorder: Option<(usize, usize)>,
    pub pending_close: Option<u64>,
    pub pending_max: Option<u64>,
    pub pending_search: Option<u64>,
    pub pending_new_tab: Option<()>,
    pub pending_detach: Option<(u64, Point)>,
    /* private fields */
}

Fields

pending_drag: Option<DragPayload>

pending_reorder: Option<(usize, usize)>

pending_close: Option<u64>

pending_max: Option<u64>

pending_search: Option<u64>

pending_new_tab: Option<()>

pending_detach: Option<(u64, Point)>

(tab_id, release_point) when a drag is released outside this bar’s rect, for a parent (e.g. GroupRow) to resolve the drop target.

Implementations

impl TabBar

pub const SOURCE_PILL_DIM_ALPHA: f32 = 0.35

Source pill’s opacity while the drag-ghost is visible; low enough to read as inactive but the slot still holds its place (no neighbour reflow).

pub const GHOST_PILL_ALPHA: f32 = 0.5

The handle is visibly lifted but remains translucent enough for a drop target to stay legible beneath it.

pub fn new( group_id_tag: &str, tabs: Vec<TabDescriptor>, active_id: u64, ) -> TabBar

pub fn closable(self, closable: bool) -> TabBar

Whether tabs close from the strip (default true). Without it no close control is drawn, reserved or announced.

pub fn without_new_tab(self) -> TabBar

No new-tab control at the end of the strip.

pub fn set_mark(&mut self, id: u64, mark: Option<TabMark>)

Mark what tab id’s content is doing, or clear the mark.

pub fn mark(&self, id: u64) -> Option<TabMark>

Tab id’s mark, if any.

pub fn mark_rect(&self, id: u64) -> Option<Rect>

Where tab id’s mark is painted, for hit-testing and tests.

pub fn take_mark_click(&mut self) -> Option<(u64, TabMark)>

A click on a tab’s sound mark, once: the host mutes or unmutes it.

pub fn set_group_focused(&mut self, focused: bool)

The host shows which window group has keyboard input: the active tab of the focused group carries a keyline in your colour, the focus colour, and the others carry the lift alone.

pub fn force_settled_for_tests(&mut self)

Pin transient pill geometry at its resting state for deterministic integration screenshots. This does not alter production animation; it only removes wall-clock sampling from visual regression tests.

pub fn is_settled_for_tests(&self) -> bool

Report whether a retained tab row has reached a static resting state. Visual tests use this after one layout pass instead of assuming that a fixed sleep covers every nested curve.

pub fn hold_hover_intent_at(&mut self, at: Duration) -> bool

Test/shot clock control for the pointer-intent dwell. Production input still arms this exclusively through on_cursor_moved.

pub fn hold_reveal_at(&mut self, at: Duration) -> bool

Hold every in-flight reveal curve at milliseconds along it. The curve runs on wall time and an offscreen frame costs more wall time than the whole curve lasts, so a capture that only steps frames would see just the endpoints — same escape as GroupRow::hold_shift_at. Returns whether any curve was running to sample.

pub fn visible_title( &mut self, i: usize, tr: &mut TextRenderer, theme: &Theme, ) -> Option<String>

Elides with an ellipsis when the pill is too narrow — a plain clip-rect used to slice the last glyph in half instead. None for a pinned pill.

pub fn tabs(&self) -> &[TabDescriptor]

pub fn tabs_mut(&mut self) -> &mut Vec<TabDescriptor>

pub fn active_id(&self) -> u64

pub fn set_active(&mut self, id: u64)

pub fn take_activation(&mut self) -> Option<u64>

Drain the tab selected by pointer, keyboard, or accessibility input. Programmatic reconciliation deliberately does not populate this edge.

pub fn is_pinned(&self, id: u64) -> bool

pub fn pin(&mut self, id: u64)

Caller ensures the tab exists; a stale entry is tolerated (filtered at render time) but should be cleaned up via unpin when the tab is removed.

pub fn unpin(&mut self, id: u64)

pub fn toggle_pin(&mut self, id: u64)

pub fn set_icon(&mut self, id: u64, icon: Option<AppImage>) -> bool

Replace tab id’s artwork. true when that changed what it paints.

pub fn set_accent(&mut self, id: u64, color: AlphaColor<Srgb>)

Tint id’s leading marker. A tab with no app_kind paints a filled dot in the leading slot; one with both tints its app glyph instead. Pass a colour read off the Theme — see Self::accent_ids.

pub fn clear_accent(&mut self, id: u64)

Drop id’s leading accent, giving the pill its leading zone back.

pub fn accent(&self, id: u64) -> Option<AlphaColor<Srgb>>

The accent set for id, if any.

pub fn set_modified(&mut self, id: u64, modified: bool)

Mark id as holding unsaved changes, or clear the mark.

pub fn is_modified(&self, id: u64) -> bool

True if id is currently marked as holding unsaved changes.

pub fn set_show_maximize(&mut self, show: bool)

Offer, or withhold, the hover-reveal maximize chip. Defaults to offered — see Self::show_maximize for when to turn it off.

pub fn remove_tab(&mut self, id: u64) -> Option<usize>

pub fn start_closing(&mut self, id: u64) -> bool

Active-id shifts to the neighbour immediately so the user never sees a “ghost active” frame during the fade. Idempotent on a tab already in closing_tabs — restarting the curve would pop the pill back to full opacity, worse than letting it finish.

pub fn cancel_close(&mut self, id: u64) -> bool

Restore a requested close whose host still owns the live tab. No metadata or focus is lost while the client asks for a save decision.

pub fn finalize_close(&mut self, id: u64) -> bool

Called by WindowGroup once its own fade-out has elapsed.

pub fn has_closing(&self) -> bool

pub fn is_closing(&self, id: u64) -> bool

True if id is mid close-fade — already gone from the live tab list but still rendering its CLOSE_FADE_MS animation. A caller that reconciles pills against its own model checks this before re-inserting a still-open item, so cancelling a close (e.g. answering “no” to a discard-unsaved-changes prompt) doesn’t pop a duplicate pill mid-fade.

pub fn reorder(&mut self, from: usize, to: usize)

pub fn cancel_drag(&mut self) -> bool

Abandon a pending or lifted tab without turning its release into a drop.

pub fn drag_in_flight(&self) -> bool

pub fn take_reorder(&mut self) -> Option<(usize, usize)>

pub fn take_close(&mut self) -> Option<u64>

pub fn close_rect_for_tests(&self, tab_id: u64) -> Option<Rect>

pub fn take_context_menu(&mut self) -> Option<(u64, Point)>

pub fn take_max(&mut self) -> Option<u64>

pub fn take_search(&mut self) -> Option<u64>

pub fn take_new_tab(&mut self) -> Option<()>

pub fn new_tab_rect(&self) -> Rect

Rect::ZERO when the pills have filled the bar and the chip is suppressed.

pub fn take_detach(&mut self) -> Option<(u64, Point)>

pub fn bar_rect(&self) -> Rect

pub fn tab_rects(&self) -> &[Rect]

pub fn inset_left(&mut self, px: f64)

Shifts the bar’s whole painted region — background, pills, hit rects — right by px, after apply_layout has already fit the row. A host drawing its own control over the bar’s left corner (e.g. an overlay sidebar’s hamburger toggle) reserves room for it here, rather than teaching the fit itself about a chip this widget doesn’t know exists. No-op past a px that would collapse the bar.

pub fn max_rects(&self) -> &[Rect]

Gated cfg(any(test, debug_assertions)) rather than cfg(test) so integration tests in other crates (which link the release-shaped lib) can resolve the chip from live geometry, matching WindowGroup::bar_for_tests.

pub fn search_rects(&self) -> &[Rect]

pub fn action_hit_rect(&self, chip: Rect) -> Rect

The pointer target of a maximize/search chip: at least the theme’s minimum pointer target on a side (HIG §9.6: 32 px), centred on the chip’s glyph rect, and never outside the bar. The painted chip stays ACTION_W wide and the pill widths the layout pins do not move, so neighbouring targets inside one pill overlap; a hover or press in an overlap resolves by priority — close, then maximize, then search — which keeps the close target its full 32 px. Rect::ZERO for a chip the reveal has not placed.

pub fn drop_index_for(&self, release_point: Point) -> usize

Insert before the first pill whose horizontal midpoint is past release_point.x; append if past every midpoint.

pub fn insert_tab(&mut self, idx: usize, desc: TabDescriptor)

Used by cross-group drag routing in GroupRow::handle_event to splice a detached tab into the target bar without forcing a full rebuild.

pub fn set_external_drag_hover(&mut self, cursor: Option<Point>)

Called by GroupRow::handle_event for every sibling bar while a child group’s tab drag is in flight. No-op while this bar has its own pending_drag in flight — the own-bar CursorMoved branch already drives hover_drop_idx, and the parent’s fan-out shouldn’t fight with it.

Trait Implementations

impl Widget for TabBar

fn test_rects(&self) -> Vec<(String, Rect)>

So a scenario clicks the rect the renderer actually painted, not a guessed coordinate. The zero-area case (chip suppressed) is filtered out by the registry.

fn is_layout_dirty(&self) -> bool

A fixed-height strip sized by its parent: only its first layout is a size change. Tab additions and removals are structural.

fn build_layout( &mut self, taffy: &mut TaffyTree, theme: &Theme, node_map: &mut HashMap<NodeId, *mut dyn Widget>, ) -> NodeId

fn apply_layout(&mut self, taffy: &TaffyTree, node: NodeId, origin: Point)

Take the geometry layout gave this node. The default keeps none, for widgets that neither draw nor hit-test.

fn draw( &mut self, scene: &mut Scene, transform: Affine, tr: &mut TextRenderer, theme: &Theme, presence: &PresenceCtx, )

Paint into scene. The default paints nothing.

fn handle_event(&mut self, event: &WindowEvent, ctx: &mut EventCtx<'_>)

Handle one input event with the runtime services for this retained node.

fn name(&self) -> &'static str

fn test_id(&self) -> Option<&str>

Stable id for the e2e test harness; None falls back to a path-based key. Must be unique across the live tree — the registry resolves on first match, so a duplicate shadows the second occurrence.

fn accessibility(&self) -> Option<AccessNode>

Role, name/description/value, and AccessState. Default None means presentational: the node is skipped and children reparent onto the parent. State must be derived, not stored so it can’t drift from draw; names must already be i18n!-resolved.

fn perform_semantic_action( &mut self, target: &str, action: &Action, _state: &mut Edits<'_>, _path: &(dyn Any + 'static), ) -> bool

Handle an action addressed to a synthetic accessibility child created by this widget. target is the opaque stable value supplied through AccessNode::with_action_target.

fn get_rect(&self) -> Rect

The rectangle this widget occupies. The default, for widgets that keep no geometry, is empty.

fn is_focusable(&self) -> bool

fn set_focus(&mut self, focused: bool)

fn is_focused(&self) -> bool

fn wants_pointer_capture(&self) -> bool

fn set_motion_reduced(&mut self, reduced: bool)

Apply the effective reduced-motion preference before the host asks this subtree whether it needs another animation frame. The default forwards recursively, making the preference a framework policy instead of an optional convention that every container has to remember to implement.

fn needs_animation_frame(&self) -> bool

App polls this in Event::AboutToWait; without it a curve would freeze partway until an unrelated event woke it again.

fn native_input_snapshot( &self, _state: &(dyn Any + 'static), _path: &(dyn Any + 'static), ) -> Option<Value>

Read-only state evidence for opt-in scheduled native input diagnostics. Called only around diagnostic inputs, never during ordinary input or paint. Keep this inexpensive and root-local; snapshots may be logged verbatim. This verifies widget state, not rendered pixels or display presentation.

fn view_only_scroll(&self, _event: &WindowEvent) -> bool

Opt in only when this wheel event changes scroll geometry and nothing else: no document edit, focus/selection, action availability, resource declaration, pending command or work that requires sync. The runner still lays out, paints and refreshes accessibility geometry. Unknown handlers stay on the full synchronization/publication path.

fn primary_vertical_scroll(&self) -> Option<PrimaryScrollRegion>

Explicit app-owned region; never search secondary children implicitly.

fn apply_primary_vertical_scroll( &mut self, _action: PrimaryScrollAction, ) -> PrimaryScrollResult

fn callback_binding(&self) -> Option<CallbackBinding>

Runtime binding inherited by descendants in a matching layout topology.

fn has_separate_document_owner(&self) -> bool

Whether this widget introduces a document owner distinct from the runner’s outer State. This is a compatibility check, never identity or authority for history access or restore.

fn history_owner(&self) -> Option<HistoryOwner>

Opaque actual custody for framework History source registration.

fn record_owners(&self) -> Vec<HistoryOwner>

Records this widget keeps open beside the document it shows, each synced on its own route: a framework app’s records in the person’s own room (crate::record::person). They take no part in this widget’s history or controls.

fn provide<'a>(&'a self, _request: &mut Request<'a, '_>)

Answer a request for a capability this widget takes part in (see capability). Declare capabilities with crate::provides!.

fn provide_mut<'a>(&'a mut self, _request: &mut RequestMut<'a, '_>)

Exclusive counterpart to Widget::provide.

fn mount_native_views(&mut self, host: &NativeViewHost<'_>)

Attach native child views through this owner’s retained lifecycle topology.

fn unmount_native_views(&mut self)

Tear native children down while their parent window still exists.

fn native_view_frame_start(&mut self)

Begin a native-view frame through this owner’s retained lifecycle topology.

fn set_platform_conventions(&mut self, conventions: PlatformConventions)

Receive host-selected platform conventions. The default propagates to retained children, keeping target-OS branches out of app code.

fn set_interaction_environment(&mut self, environment: InteractionEnvironment)

Receive the host’s current input capabilities. The default propagates through retained containers, so app code does not need device branches.

fn sync(&mut self, state: &(dyn Any + 'static), path: &(dyn Any + 'static))

Pull model state into this widget before layout. The default syncs the children Widget::children_mut returns; a widget overrides it only to read state of its own, or to sync children it does not expose there.

fn update( &mut self, state: &(dyn Any + 'static), path: &(dyn Any + 'static), ) -> bool

Notice, between frames, state that lives outside the document (a chrome revision, a momentum scroll still ticking) and report whether anything changed. The default updates every child Widget::children_mut returns, without short-circuiting, so a container never freezes its descendants at build-time state; a widget overrides it to check state of its own and then forward.

fn settle(&mut self, edits: &mut Edits<'_>, path: &ExId)

Apply, after the sync pass, what the widget took up there and must write: a worker’s answer, a chooser’s file, an event a child queued. Writes go only through typed actions on edits (a resource’s dispatcher); the host syncs again when the document changed. The default settles the children Widget::children_mut returns.

fn measure( &mut self, _known: Size<Option<f32>>, _available: Size<AvailableSpace>, _text_renderer: &mut TextRenderer, ) -> Size<f32>

fn layout_info(&self) -> Option<LayoutInfo>

Read-only resolved decisions for widgets with an explicit layout policy. None means the widget has no such policy; ordinary manual widgets remain valid. Values are available after build/settlement and carry real origins.

fn adjust_layout_style( &mut self, _taffy: &mut TaffyTree, _node: NodeId, _text: &mut TextRenderer, ) -> bool

Adjust this node’s style using its allocated size, before final geometry is applied. Return true only when the style changed (or an inherited decision child hooks read). An override may measure its owned children through ordinary references, entering their callback binding when present. Never reenter descendants through the raw node map while borrowing their parent, change topology, or build another layout tree. The shared host solver visits every registered widget, repeats layout at most eight times and skips a frame that does not settle.

fn observe_physical_input(&mut self, _input: PhysicalInput)

Observe this app’s ordinary foreground physical input before framework shortcuts consume it. Keep feedback ephemeral; this is not an input grant.

fn children(&self) -> Vec<&dyn Widget>

fn for_each_child(&self, visitor: &mut dyn FnMut(&dyn Widget))

Allocation-free read-only child traversal. Existing custom containers inherit a compatibility adapter over Self::children; toolkit containers override this to walk their retained storage directly.

fn children_mut(&mut self) -> Vec<&mut dyn Widget>

fn local_resource_operation_handlers(&self) -> &'static [&'static str]

Effect/view operation type ids this widget can actually dispatch.

fn resource_operation_handlers(&self) -> HashSet<String>

fn as_any(&self) -> Option<&(dyn Any + 'static)>

Downcast to the concrete widget, for hosts and tests that reach a known widget through dyn Widget. Default None (a widget may borrow and so not be 'static); a widget opts in with Some(self), and a Decorator answers itself.

fn as_any_mut(&mut self) -> Option<&mut (dyn Any + 'static)>

fn reveal_descendant(&mut self, target: *const dyn Widget) -> bool

Reveal a newly keyboard-focused descendant inside any enclosing viewport. Containers override this to scroll; ordinary widgets simply recurse toward the target and report whether it was found.

fn child_clip_rect(&self) -> Option<Rect>

Absolute logical clip applied to ordinary children during painting and pointer routing. Inspectors and enclosing scroll regions must respect this boundary instead of treating clipped descendants as visible extent.

fn take_action_palette_request(&mut self) -> Option<ActionAddress>

One-shot request to open the host’s action palette directly at a typed resource action. Parameter collection and permission checks remain host policy; widgets only name an address already present in resources().

fn take_search_request(&mut self) -> bool

One-shot request to open the host’s search palette, the same one the platform search shortcut opens. An app’s own search button latches it so search stays one shared host surface rather than an app overlay.

fn cursor_shape(&self, _point: Point) -> Option<CursorIcon>

point is logical coords, same space as Widget::get_rect; None defers to the default arrow. The host hit-tests the whole tree via node_map and picks the smallest-area claim, so containers need not override this.

fn claims_raw_touch(&self, _point: Point) -> bool

Opt out of touch-to-pointer emulation for contacts that begin at point (logical coords, same space as Widget::get_rect).

fn tooltip(&self) -> Option<&str>

Revealed after a dwell over the widget’s rect, via the toolkit’s one tooltip mechanism (crate::widget::tooltip::TooltipHost), hit-tested like cursor_shape so containers need not forward it. An icon-only control should also use this as its accessible name.

fn tooltip_side(&self) -> TooltipSide

Which side of the control its tooltip goes: below by default, beside it for a control in a vertical rail.

fn tooltip_target_at(&self, point: Point) -> Option<(Rect, String)>

fn is_default_keyboard_focus(&self) -> bool

Preferred control when its app is explicitly activated without a valid saved control. Hosts still enforce visibility, enabled state and scope.

fn keyboard_input_scope(&self) -> Option<u64>

Exact app instance whose non-text shortcuts this subtree owns when activation has no control target. Unbound desktop chrome may declare the active tab; component boundaries default to their captured owner.

fn set_invalid(&mut self, _invalid: bool)

The form’s validation verdict for this control, set by Field::with_error: an invalid control edges itself in danger ink and reports invalid to assistive technology. Controls without a field face ignore it.

fn focus_requested(&mut self, target: Option<NodeId>, tree: &TaffyTree)

An explicit runner focus request, after resolving the actual keyboard owner. Retained flags and layout restoration are not user gestures. Containers can observe this to reveal the owning viewport.

fn wants_tab_input(&self) -> bool

Whether a focused widget owns Tab instead of the host’s focus traversal. This is deliberately opt-in: ordinary form fields and controls retain platform-standard Tab/Shift+Tab navigation, while a code editor or terminal can receive the key for indentation or completion.

fn ime_cursor_rect(&self) -> Option<Rect>

Caret rectangle for the platform input method, in window-logical coordinates. Returning Some enables IME for the focused widget and positions its candidate window; non-text controls keep the default None and therefore disable IME.

fn traps_focus(&self) -> bool

While any widget answers true, the host restricts Tab/directional focus to this subtree (wrapping at the ends) and restores the prior focus once it goes back to false. Default false.

fn synthetic_accessibility_rect(&self, _path: &[usize]) -> Option<Rect>

Geometry for an immediate-mode semantic child from AccessNode::children. The path is its child-index path beneath this widget’s accessibility node. Returning a rect lets AccessKit activation inject the same click as pointer input.

fn focus_synthetic_accessibility(&mut self, _path: &[usize]) -> bool

Move this widget’s own immediate-mode focus to a synthetic semantic child. Retained widgets continue to use the ordinary taffy focus path.

fn accessibility_child_parent(&self, _child_index: usize) -> Option<usize>

Reparent one retained children entry beneath a synthetic child returned by accessibility. The returned index addresses AccessNode::children for this frame. Collections use this to place a real interactive row delegate inside its virtual ListItem/TreeItem instead of exporting a duplicate.

fn accessibility_child_path(&self, child_index: usize) -> Option<Vec<usize>>

Reparent one retained children entry beneath a nested path of synthetic children returned by accessibility.

fn accessibility_represents_child(&self, _child_index: usize) -> bool

Whether one retained children entry is already represented in this widget’s own synthetic accessibility tree, so the bridge must not export it a second time. A host that publishes a child’s semantics itself (to add its own controls inside the same dialog) answers true for that child; assistive technology then sees one copy, not two.

fn perform_action( &mut self, _action: &Action, _key_path: &[u64], _state: &mut Edits<'_>, _path: &(dyn Any + 'static), ) -> bool

Perform an accessibility Action on this widget, or on one of its synthetic accessibility nodes. May mutate the CRDT like handle_event.

fn is_enabled(&self) -> bool

A disabled (false) widget is excluded from focus traversal, must reject input in handle_event, and renders dimmed (see DISABLED_ALPHA).

fn ime_requires_deferred_ack(&self) -> bool

This field needs a host that consumes deferred receipts. Ordinary native Wayland windows must not advertise it until they have that delivery path.

fn start_deferred_text(&mut self) -> Option<Receipt>

Begin one bounded deferred session after explicit host consent, preserving the existing original-field fingerprint. This grants no microphone access.

fn commit_deferred_text(&mut self, text: &str) -> Option<Receipt>

A private asynchronous final. None leaves ordinary synchronous IME dispatch to the host. A receipt binds this original field and must be acknowledged before the host releases its private recovery transcript.

fn ime_purpose(&self) -> Option<ImePurpose>

The focused widget wants platform text input (Wayland text-input-v3, native IMEs elsewhere). None is intentionally the default: enabling an IME for buttons, canvas tools or games makes the compositor raise an on-screen keyboard over content that cannot accept the committed text.

fn ime_multiline(&self) -> bool

Whether the original focused editor accepts line feeds as text. This is field policy, never inferred from a multiline accessibility presentation. Wrappers inherit only one unambiguous child at their active IME caret.

fn ime_edit_fingerprint(&self, key: &[u8; 32]) -> Option<[u8; 32]>

Opaque local invalidation of deferred input, including selection edits that leave the caret rectangle unchanged. The host supplies an ephemeral secret key; no text or selection is retained in the resulting digest. The default shares the accessibility door and excludes protected or read-only controls. Text controls can override it to avoid cloning text.

fn presented(&self) -> bool

Default true; the exception is a widget standing in for a process that has started but not drawn. Must latch: once true, never false again for the same content, or an un-presenting widget would make a window vanish mid-resize. What shows meanwhile is decided by Widget::opening.

fn opening(&self) -> bool

True once waiting long enough, while not yet presented, that showing nothing would read as broken. Delayed so a fast open never flashes an indicator.

fn text_review(&self) -> Option<(usize, String)>

(caret_byte, text), byte offset on a char boundary. The host diffs this before/after an event so caret-only moves (arrows, Home/End) get announced, not just typing.

fn on_external_event( &mut self, _payload: &str, _state: &mut Edits<'_>, _root: &(dyn Any + 'static), )

Delivers an out-of-band string payload from crate::app::UserEvent::External (e.g. a worker thread streaming output into a status log). Default no-op; the App redraws and re-syncs after dispatch, so mutating state here is enough.

fn on_nav_gesture( &mut self, dir: NavDirection, state: &(dyn Any + 'static), path: &(dyn Any + 'static), ) -> bool

Global back/forward gesture (swipe/edge-pull), recognised by crate::gesture::NavGestureRecognizer and delivered to the whole tree; return true once consumed. Default forwards to children, so a widget that owns history becomes swipe-navigable for free.

fn nav_availability(&self) -> NavAvailability

Which directions Self::on_nav_gesture would consume now. A widget that owns history overrides this beside on_nav_gesture.

fn take_focus_reset(&mut self) -> bool

One-shot (reading MUST clear it) signal to move focus to this subtree’s first focusable widget after the next rebuild. Only consulted under crate::app::App::autofocus_on_structure_change; a wizard raises it on step transitions.

fn take_accessibility_request(&mut self) -> Option<AccessibilityRequest>

One-shot (reading MUST clear it) request to change the window’s accessibility preferences, raised by a control the person used. The host applies it before the next frame. Default forwards the first request found among the children.

fn dev_route(&self) -> Option<RouteSnapshot>

Route history when this widget, or one it contains, is a Router.

fn restore_dev_route(&mut self, route: &RouteSnapshot) -> bool

Put route back. Returns whether a router in this subtree accepted it.

fn appearance_intent(&self) -> Option<AppearanceIntent>

Theme/high-contrast/reduced-motion/scale, polled under crate::app::App::appearance_reconcile — how a settings pane re-themes the running app live without a back-channel. Level-triggered; the App recurses Self::children itself, so containers need not forward it. First Some wins.

fn needs_idle_sync(&self) -> bool

Whether sync still needs to run on idle frames without input or collab events — e.g. waiting out a document-adoption grace window.

fn take_committed_action(&mut self) -> Option<Vec<ChangeHash>>

The affordance-driven twin of the Ctrl+K palette: when a widget’s own control dispatches the same tilo_actions action its ActionSpec exports, it reports the document heads captured just before here, so the host can record one undo boundary the same way a palette dispatch does. Rising-edge: reading MUST clear it.

fn keeps_undo_step_open(&self) -> bool

Whether the undo step this widget’s last reported boundary opened stays open for the actions that continue it — the rest of a word typed a keystroke at a time. A hosted component then closes the step at the widget’s next boundary, or before an undo, a save or a merge, instead of after this event. Answered by the widget itself, never its children.

fn set_undo_status(&mut self, _status: &mut dyn FnMut() -> UndoStatus)

Host → widget: the live state of the undo history, published once per frame to every laid-out widget.

fn take_undo_request(&mut self) -> Option<UndoRequest>

Widget → host: an undo or redo the user asked for.

fn handle_local_undo_request(&mut self, request: UndoRequest) -> bool

Offer a host keyboard undo/redo shortcut to focused widget-local history before the application document consumes it.

fn apply_room_action( &mut self, _doc: &mut Edits<'_>, _type_id: &str, _payload: &[u8], ) -> bool

Apply an action another app in this room published, if this app owns the document — lets an app address a document it doesn’t hold by saying what should happen instead of writing bytes directly, keeping each document to one writer. An unrecognised type_id is silently declined, not an error.

fn start_operation( &mut self, op: &ResourceOperation<'_>, doc: &mut Edits<'_>, path: &ExId, ) -> Result<Option<ResourceOperationStart>, String>

Admit an exported effect or view operation: the one entry every handler implements. Document operations never enter it.

fn semantic_readers(&self) -> &'static [RegisteredSemanticReader]

Inert immutable-reader registrations owned by this actual widget. Registration alone supplies no qualified owner frame or disclosure.

fn poll_resource_operation( &mut self, invocation: InvocationId, cancellation_requested: bool, doc: &AutoCommit, path: &ExId, ) -> Option<InvocationUpdate>

Poll one admitted operation without blocking the UI thread.

fn next_wake_deadline(&self) -> Option<Instant>

Earliest wall-clock deadline at which this subtree needs a sync/redraw even if there is no input. Unlike needs_animation_frame, this keeps the event loop asleep until the requested instant and is appropriate for filesystem/status polling rather than animation.

fn modal_capture(&self) -> Option<Rect>

Some(rect) when this subtree holds an open modal, its panel box. While any widget reports Some, the host suppresses its own global focus shortcuts and swallows unhandled pointer presses so nothing behind the modal is clickable. Containers MUST forward (the default does, via first Some among children).

fn take_structure_dirty(&mut self) -> bool

True if this subtree’s structural composition (children inserted/removed) changed since the last frame; the App rebuilds the taffy tree when so. Reading clears it. The default drains every retained child (no short-circuit, so no child keeps a stale flag) and reports whether any was dirty; a leaf has no children and reports false. A container that changes its own child list sets its own flag and ORs it with this traversal.

fn take_structure_change(&mut self) -> StructureChange

Self::take_structure_dirty, saying whether the frame’s damage can still describe the rebuild (StructureChange::Described). Reading clears what take_structure_dirty clears; the two must agree on whether there is a change. The default is the flag, as a StructureChange::Rebuild: only a widget that knows every pixel its change touches lands in its own damage says less, and a container forwards a child’s StructureChange::Described only by overriding this.

fn has_pending_visual_work(&self) -> bool

Work already requested by this view whose completion will replace a placeholder. Unlike animations, this can be awaited by still captures.

fn has_transient_feedback(&self) -> bool

Temporary feedback currently presented, such as a save acknowledgement. Captures may intentionally include it; scene-invariance checks can wait for it to disappear separately from unfinished placeholder work.

fn needs_redraw(&self) -> bool

Default true (dirty every frame). Opt into incremental redraw by tracking a dirty: bool, setting it in handle_event/sync, and clearing it in mark_drawn(). Containers MUST forward: dirty iff any descendant is.

fn collect_damage(&self, regions: &mut Vec<Rect>)

Logical-pixel bounds whose visual output differs from the last frame.

fn damage_covers_own_box(&self) -> bool

Whether, after this frame’s draw, this widget’s own Self::collect_damage covers every pixel a relayout changed by moving or resizing its layout box: a host that repaints where moved widgets were and are may then leave this widget’s box to it (its children’s boxes still count). A block editor that grew by a paragraph says where its blocks were and are; the default does not claim it.

fn mark_drawn(&mut self)

Called after this widget’s scene lands in the composed frame, to clear a dirty flag. Default forwards to children.

fn release_scene_cache(&mut self)

Release retained encoded-scene storage in this subtree without marking its visual/model state dirty. Outer caches call this after a successful reuse: while the outer display list is authoritative, keeping byte-for-byte descendant encodings only duplicates memory. A later outer rebuild causes descendants to record/cache normally.

fn layout_needs_measure(&self) -> bool

Whether a layout_dirty frame needs taffy to re-solve sizes (compute_layout) rather than just reposition already-solved boxes. Scrollable is the motivating override: it translates its origin in apply_layout without changing any taffy size, so re-solving on every scroll frame is pure waste.

fn paint_bounds(&self) -> Rect

Everything this widget paints, children included; draw_child skips the draw when it misses the viewport. Override for widgets that paint past their own rect.

fn draw_overlay( &mut self, scene: &mut Scene, transform: Affine, text_renderer: &mut TextRenderer, theme: &Theme, presence: &PresenceCtx, )

Top-layer pass, run once after the whole draw recursion, so anything emitted here composites above every sibling regardless of tree order — the toolkit’s overlay mechanism for content that escapes its layout box (an open Dropdown, a popover). Default recurses children_mut.