/**
 * Keeps a touch that lands on the open panel from scrolling the page behind
 * it.
 *
 * `overscroll-behavior: contain` is on the message list already, and it does
 * the job for the case it covers: a list that can scroll, dragged past its
 * own end. It has nothing to say about the cases that actually leak. A short
 * conversation does not overflow, so the list is not a scroll container at
 * all and the touch goes straight through to the document — which is what a
 * reader on an iPhone sees as the page sliding around underneath a chat that
 * looks like it should be holding still. The same happens for a touch that
 * starts on the title bar or beside the input.
 *
 * So the rule is decided here instead: a touch on the panel may scroll
 * something inside the panel, and otherwise it does nothing. On the first
 * move of each gesture the controller looks along the touch's own path —
 * `composedPath`, so a scroller inside a consumer's component counts too —
 * for something that can still travel in the direction the finger is going.
 * Finding one, it stands aside for the rest of the gesture; finding none, it
 * cancels the move, and iOS then takes the whole gesture as "not a scroll".
 *
 * Two touches are left alone: that is a pinch, and zooming is the reader's.
 * A move that is no longer cancelable is left alone too — the browser has
 * already committed to scrolling, and `overscroll-behavior` is what keeps
 * that inside the list.
 *
 * @implements {ReactiveController}
 */
export class ScrollLockController implements ReactiveController {
    /** @param {LitElement} host */
    constructor(host: LitElement);
    hostUpdated(): void;
    hostDisconnected(): void;
    #private;
}
import type { ReactiveController } from 'lit';
import type { LitElement } from 'lit';