example window controls

Window controls

The title-bar control cluster (close / minimize / maximize / focus) is rendered from a registry plugins can extend, reorder, hide, or replace per-window. Built-in controls live in the same registry as plugin controls, addressed by the stable ids core/minimize, core/maximize, core/focus-tab, core/close. (Detach and reload moved into the title-bar three-dots menu and are no longer registry controls.)

This is Layer 2 of the four-layer window-chrome customization framework. See Window themes for Layer 1.

---

Recipe 1 — Reorder built-in controls per window

Move the close button to the leftmost position on a specific native window:

wp.os.registerWindow( {
    id:     'my-plugin/dashboard',
    title:  'Dashboard',
    icon:   'dashicons-dashboard',
    width:  640, height: 480,
    minWidth: 320, minHeight: 200,
    appearance: {
        controls: {
            order: [ 'core/close', 'core/minimize', 'core/maximize' ],
        },
    },
    render: ( body ) => { body.textContent = 'Hello'; },
} );

Controls listed in order render in that order; controls not listed keep their registry order and append after.

Recipe 2 — Hide a built-in for one window

wp.os.applyWindowControls( 'edit-post', {
    hide: [ 'core/focus-tab' ],
} );

Other windows retain the full set. Pass null to clear the override.

Recipe 3 — Add a custom control inside the cluster (window-scoped)

A control declared inline never enters the global registry — it lives only on this window:

wp.os.applyWindowControls( 'edit-post', {
    custom: [
        {
            id:    'my-plugin/star',
            label: 'Star this draft',
            icon:  'dashicons-star-filled',
            placement: 'controls', // alongside close/min/max
            order: 5, // before core/minimize (order 10)
            onClick: ( ev ) => {
                console.log( 'starred', ev );
            },
        },
    ],
} );

placement: 'controls' puts the button inside the cluster. 'left' and 'right' are accepted but currently route through the legacy title-bar-button registry — see Connect to a window for the established pattern.

Recipe 4 — Register a control globally (cross-window)

When the same control should appear in many windows, register it via wp.os.registerWindowControl() with a match predicate:

plugin.php

add_action( 'admin_enqueue_scripts', function () {
    wp_register_script(
        'my-plugin-controls',
        plugins_url( 'controls.js', __FILE__ ),
        array( 'openstation' ),
        '1.0.0', true
    );
    wp_enqueue_script( 'my-plugin-controls' );
} );
openstation_register_window_control_script( 'my-plugin-controls' );

controls.js

wp.os.whenReady( () => {
    wp.os.registerWindowControl( {
        id:    'my-plugin/info',
        label: 'Info',
        icon:  'dashicons-info',
        placement: 'controls',
        order: 5,
        match: ( win ) => win.config.url?.includes( 'post.php' ) ?? false,
        owner: 'my-plugin-controls',  // for live unregister on deactivation
        onClick: ( win ) => {
            console.log( 'info clicked on', win.id );
        },
    } );
} );

The owner field is the WP script handle. Deactivation drops every control with this owner without F5.

Recipe 5 — Hide a built-in globally

wp.os.unregisterWindowControl( 'core/focus-tab' );

Re-register at any time to bring it back; the registry is a Map and entries replace by id.

Recipe 6 — Move the controls cluster to the left edge

wp.os.applyWindowControls( 'my-plugin/dashboard', {
    placement: 'left',
} );

Sets the os-window__controls--left class on the cluster, which moves it to the start of the title bar. A theme that draws the title bar differently can restyle that class.

Recipe 7 — Mutate the resolved list with a filter

When you don't want to register or unregister, use the os.window.chrome.controls filter to mutate the list at paint time:

wp.hooks.addFilter(
    'os.window.chrome.controls',
    'my-plugin/never-close-the-shop',
    ( controls, ctx ) => {
        if ( ctx.placement !== 'controls' ) return controls;
        // Hide close on the woocommerce shop window.
        if ( ctx.config.url?.includes( 'admin.php?page=wc-admin' ) ) {
            return controls.filter( ( c ) => c.id !== 'core/close' );
        }
        return controls;
    }
);

---

Hooks

PHP

Hook	Type	Signature	Purpose
openstation_window_control_script_registered	action	( string $handle )	Fires after openstation_register_window_control_script() succeeds.
openstation_window_control_registered	action	( string $id, array $entry )	Fires after openstation_register_window_control() stores metadata.

JavaScript

Hook	Type	Signature	Purpose
os.window.chrome.controls	filter	( controls, { windowId, config, placement } ) => controls	Mutate the resolved per-placement control list. Stable.
os.window.chrome.applied	action	( { windowId, layer } )	Fires after a paint completes. layer is 'controls' for this layer. Stable.

---

API surface

Function	Purpose
wp.os.registerWindowControl( def )	Register a global control. Throws on validation failure.
wp.os.unregisterWindowControl( id )	Drop by id. No-op if not registered.
wp.os.listWindowControls()	Snapshot for tooling / inspectors.
wp.os.applyWindowControls( windowId, override )	Per-window mutation at runtime. Pass null to clear.
WindowConfig.appearance.controls	Per-window declaration at registration time.