/**
 * Returns `true` when `document.activeElement` is inside a nested top-layer
 * descendant of `container` (a `[popover]`, `<dialog>`, `[role="dialog"]` or
 * `[role="alertdialog"]` that is itself a descendant of `container`).
 */
export declare function isNestedLayerFocused({ container }: {
    container: HTMLElement;
}): boolean;