import { CSSProperties, RefObject } from 'react';
export type ThreadPopupPlacement = "down" | "up";
/** Opens a row's comment popup below its anchor, flipping above only when it fits there but not below. */
export declare const useThreadPopupPlacement: (anchorRef: RefObject<HTMLElement | null> | undefined, isOpen: boolean) => ThreadPopupPlacement;
export declare const getPlacementOverrideStyle: (placement: ThreadPopupPlacement) => CSSProperties;
/**
 * Fixed-position style for a row popup that is portaled out of its table.
 *
 * Anchoring inside the row means the popup is part of the table's layout, so on
 * a short table it overflows and makes the table scroll. Rendered to the body
 * instead, it overlays the page and the table keeps its own size — but it then
 * needs viewport coordinates, and the space that decides up vs down is the
 * viewport rather than the table.
 *
 * Returns undefined until measured, so callers can hold the popup back for a
 * frame instead of flashing it at the top-left corner.
 */
export declare const useFixedThreadPopupStyle: (anchorRef: RefObject<HTMLElement | null>, isOpen: boolean) => CSSProperties | undefined;