import { TargetableTricklingEvent } from './TargetableTricklingEvent.js';
import type { Widget } from '../widgets/Widget.js';
/**
 * An event which contains the state of modifier keys. This is an abstract class
 * and must be implemented in child classes.
 *
 * @category Event
 */
export declare abstract class ModifierEvent extends TargetableTricklingEvent {
    readonly userCapturable: true;
    /** Is shift being pressed? */
    readonly shift: boolean;
    /** Is control being pressed? */
    readonly ctrl: boolean;
    /** Is alt being pressed? */
    readonly alt: boolean;
    constructor(shift: boolean, ctrl: boolean, alt: boolean, target: Widget | null);
}