src/vs/workbench/contrib/notebook/browser/notebookEditor.ts/NotebookEditor/hasFocus
class NotebookEditor:	override hasFocus(): boolean {
		const activeElement = document.activeElement;
		const value = this._widget.value;

		return !!value && (DOM.isAncestor(activeElement, value.getDomNode() || DOM.isAncestor(activeElement, value.getOverflowContainerDomNode())));
	}