import { IDisposable } from '@lumino/disposable';
import { ISignal } from '@lumino/signaling';
import { DocumentRegistry } from '@jupyterlab/docregistry';
import { NotebookPanel, INotebookModel } from '@jupyterlab/notebook';
/**
 * A notebook widget extension that adds a button to the toolbar.
 */
export declare class NotebookFontsButton implements DocumentRegistry.IWidgetExtension<NotebookPanel, INotebookModel> {
    readonly widgetRequested: ISignal<any, void>;
    /**
     * Create a new extension object.
     */
    createNew(panel: NotebookPanel, context: DocumentRegistry.IContext<INotebookModel>): IDisposable;
}