src/vs/workbench/contrib/notebook/browser/services/notebookEditorServiceImpl.ts/NotebookEditorWidgetService/_disposeWidget
class NotebookEditorWidgetService:	private _disposeWidget(widget: NotebookEditorWidget): void {
		widget.onWillHide();
		const domNode = widget.getDomNode();
		widget.dispose();
		domNode.remove();
	}