/** Start watching for a mousedown outside an open listbox. */
export declare function listenOutside(handler: (e: MouseEvent) => void): void;
/** Stop watching for a mousedown outside a listbox. */
export declare function unlistenOutside(handler: (e: MouseEvent) => void): void;
/** Keep the active option of an open listbox in view. */
export declare function scrollOptionIntoView(host: Element, open: boolean, index: number, id: string): void;