adsk-forge-LevelSectionPanel-step8

class LevelSectionPanelExtension extends Autodesk.Viewing.Extension {
    constructor(viewer, options) {
        super(viewer, options);
        this.panel = null;
        this.createUI = this.createUI.bind(this);
        this.onToolbarCreated = this.onToolbarCreated.bind(this);
    }

 // ...
}