iframe

The component is small enough to quote almost entirely:

class FieldIframePreview extends Component {
    static template = "website.iframeWidget";
    static props = { ...standardFieldProps };
    setup() {
        this.state = useState({ isMobile: false });

        useBus(this.env.bus, "THEME_PREVIEW:SWITCH_MODE", (ev) => {
            this.state.isMobile = ev.detail.mode === "mobile";
        });
    }
}

It renders the website.iframeWidget template and keeps one piece of state, whether to show a mobile viewport. That state is driven entirely by an event on the environment bus.

The descriptor is one line: { component: FieldIframePreview }. No display name, no supported types, no options.

This is the frame you look at when picking a website theme, and the desktop and mobile toggle above it is what this widget is listening to.

It is not a general-purpose embed. If someone on your team wants to show a partner portal, a dashboard from another system or a document preview inside an Odoo form, this widget is not the tool, and reaching for it will produce a frame with no way to toggle and no configuration.

The standard use, on the theme picker:

<field name="theme_preview_url" widget="iframe"/>

Applying it elsewhere renders the frame, but the mobile toggle will never fire because nothing outside the theme screen emits the event it waits for.

The widget does not own its own toggle. It subscribes to an event on the shared environment bus:

useBus(this.env.bus, "THEME_PREVIEW:SWITCH_MODE", (ev) => {
    this.state.isMobile = ev.detail.mode === "mobile";
});

Something else has to fire THEME_PREVIEW:SWITCH_MODE with a mode in its detail. In standard Odoo that something is the theme preview screen's own controls.

Put this widget on an ordinary form and it renders, but isMobile stays false forever, because nothing on that form emits the event. Nothing errors and nothing warns. The frame simply never switches, which reads as a broken toggle rather than an absent one.

If you do want that behavior on your own screen, the fix is not to change the widget. Emit the same event on the environment bus from your own component and this widget will respond, because the bus is shared rather than scoped to the theme screen.

No change. Diffing the registration between the 19.0 and 20.0 branches shows the same single-key descriptor, still with no options and no supported types.