/**
 * Runs a callback everytime a new object is attached to a given node.
 * The callback can optionally return a disposer which will be run when the child is detached.
 *
 * The optional options parameter accepts and object with the following options:
 * - `deep: boolean` (default: `false`) - true if the callback should be run for all children deeply
 * or false if it it should only run for shallow children.
 * - `fireForCurrentChildren: boolean` (default: `true`) - true if the callback should be immediately
 * called for currently attached children, false if only for future attachments.
 *
 * Returns a disposer, which has a boolean parameter which should be true if pending detachment
 * callbacks should be run or false otherwise.
 *
 * @param target Function that returns the object whose children should be tracked.
 * @param fn Callback called when a child is attached to the target object.
 * @param [options]
 * @returns
 */
export declare function onChildAttachedTo(target: () => object, fn: (child: object) => (() => void) | void, options?: {
    deep?: boolean;
    fireForCurrentChildren?: boolean;
}): (runDetachDisposers: boolean) => void;