get parentApp() {
		if (typeof this._parentApp === "undefined") {
			if (
				typeof this.ancestor !== "undefined" &&
				typeof this.ancestor.getRootAncestor === "function"
			) {
				// the `app` property is only defined in the world "root" container
				this._parentApp = this.ancestor.getRootAncestor().app;
			}
		}
		return this._parentApp;
	}
returns the parent application (or game) to which this renderable is attached to
@return {Application} the parent application or undefined if not attached to any container/app