onInit() {
            BaseController.prototype.onInit.apply(this, arguments);

            this._defineIllustrationSizes();
            this._defineViewModel();
            this._initThemePicker();
            this._setAppTheme();
            Promise.all([IllustrationPool._registerDefaultSet(), this._registerTntIllustrationSet()]).then(this._setIllustrations.bind(this));
            this._showWelcomeMessage();
        }
Lifecycle method called when the controller is initialized.
@override