Controls

Every control here binds theme tokens, never literals, and works under either theme engine.

TabStrip

A horizontal tab strip with drag-to-reorder and a FLIP neighbour-slide, cross-strip transfer between siblings sharing a DragOverlay canvas, pin, lock, duplicate and close actions, a new-tab button, and a themable active-tab indicator. It drives any ITabHost; the per-tab template binds to ITabItem, so a file manager's panes and an agent app's sessions back a tab without a shared base class. Optional affordances are gated by the host's capability flags, so a simpler host gets a simpler strip. TabActivity renders a live status on background tabs, orthogonal to the identity icon.

The sidebar framework

Two pieces, extracted whole so the feel survives reuse. SidebarDockController owns the window-side mechanics: the reserved column at rail width when unpinned and at the persisted, clamped docked width when pinned, with the cubic-ease dock morph between them, live width tracking while pinned, and the passive edge pull on the seam with a dwell before the reveal. SidebarPeekBehavior is the hover-peek choreography: open on a HoverIntent dwell, never on a straight pass, close on leave after a grace, held open only by text entry inside the surface. The app implements ISidebarHost for the state; SidebarDockOptions holds the tuned constants.

Fields and pickers

Control	What
AlloyTextBox	A restyled native TextBox, so caret, selection, IME and undo come from the primitive. Optional uppercase label, leading glyph, clear affix, status glyph, stepper, prefix and suffix segments, helper text. Variants sm, search, area, number.
AlloyTextArea	The labelled multi-line field over an AlloyTextBox. Mono for line-oriented lists.
AlloySelect	A restyled native ComboBox for pick-one lists.
AlloyDropDown	The trigger-anchored frame for rich popovers: search, sections, trees.
TokenBox	A text field with trigger-char autocomplete, $token by default, over TokenCompletion.
HotkeyBox	Click and press a chord; stores it as a portable Mod+ string.
FontSizeStepper	The shared text-size stepper with step, clamp, flash readout and tooltips.

Overlays and settings

OverlayCard is the modal-overlay shell with header, body and footer slots and a real, keyboard-accessible close button that raises a bubbling CloseRequested; the window handles it once for every overlay. PreferencesOverlay is the settings shell on top of it: a search-first section rail driven by PrefsNavigator, a flat list of PrefSection, and the section bodies bound to Selected. PreferenceRow is one settings row, title and description left, a trailing control right. CommandPaletteView is the palette.

Chrome and motion

• DrawerPull, the gold tab on a seam. Edge picks the shadow, PointsLeft the chevron.
• BusySpinner, driven by a composition animation so it keeps turning while the UI thread is blocked, which is exactly when you need it.
• MorphPane, a pane whose width morphs on the render thread as a clip rather than a layout animation, so a busy UI thread never stutters it.
• HeightMorph, animates its own height toward its child's, so a state swap morphs instead of snapping.
• CopyGlyph, the copy affordance that flips to a check for a beat as the receipt.
• AlloySplashWindow, the launch splash, a token-themed card with a live status line.
• LogViewer and LogViewerWindow, the embeddable log tail; see Services.

Attached behaviours

Property	What
HoverIntent	The affordance wakes only after the pointer dwells; a straight pass never flashes chrome. Declarative via RevealClass, or imperative for pointer-math zones.
AutoScroll	Keeps a ScrollViewer pinned to the bottom as content grows, only while the user is already at the end.
InlineRename	The label-to-box swap: focus and select-all when editing starts, Enter and lost-focus commit, Escape cancels.
OverlayScrollbars	The macOS behaviour where the bar also fades in while content moves.
TextCaret	A caret drawn at the true text-end, because Avalonia's lands one or two DIP left at end of line.
MacOSTitleBar	The thick, transparent macOS title bar for extended-client-area windows.

Typography

FontCatalog is the faces one axis offers, UI, mono or display, and how to apply the picked one: the family, its own OpenType features, and its own plain and emphatic weights, because neither travels with a family name. FontFaceDef is one bundled face. FontFaceVerification checks a face delivers what it declared against the live font manager, because Avalonia answers a missing weight by emboldening and a missing italic by shearing, silently. CapCentering optically centres a capital in a box using the face's real cap height.