export interface PopupLayer {
    trigger: () => HTMLElement | null;
    popup: HTMLElement;
    close: () => void;
}
export declare function registerPopupLayer(layer: PopupLayer): () => void;
/** 还开着的弹层里最晚打开那位的顺序号；一个都没有则 0。遮罩层用它判断自己有没有被弹层压住。 */
export declare function latestPopupLayerOrder(): number;
export declare function isTopPopupLayer(layer: PopupLayer): boolean;
export declare function popupLayerElements(layer: PopupLayer): HTMLElement[];
export declare function closePopupChildren(popup: HTMLElement): void;