export interface OverlaySlot {
    readonly key: string;
    render(): string;
}
export interface OverlaySink {
    setOverlay(text: string): void;
}
export declare class OverlayComposer {
    private readonly sink;
    private readonly order;
    private readonly slots;
    private dirty;
    constructor(sink: OverlaySink, order: readonly string[]);
    register(slot: OverlaySlot): void;
    markDirty(key: string): void;
    flush(): void;
    invalidate(): void;
}