/**
 * A <flexible-container> pins its height to its content and animates between measurements, but it
 * measures on light-DOM mutations only: a height change that happens inside a child's shadow root —
 * a drawer sliding open on a CSS transition — is invisible to it, and the container keeps clipping
 * at the old height until something unrelated (a tab switch, a window resize) makes it look again.
 *
 * A nested <flexible-container> solves this for itself by announcing its animation to every
 * enclosing one, which then stops clipping (height auto, no transition) until the child has
 * settled and measures again. This is that protocol for a panel that animates with CSS instead:
 * call `announce` whenever a change that moves the panel's height begins; the announcement is
 * held open for the duration and extended by any further call inside it.
 */
export declare const createHeightChangeAnnouncer: (el: HTMLElement) => {
    announce(durationMs: number): void;
    dispose(): void;
};