src/vs/workbench/contrib/notebook/browser/view/cellParts/markupCell.ts/MarkupCell/updateFoldingIconShowClass
class MarkupCell:	private updateFoldingIconShowClass() {
		const showFoldingIcon = this.notebookEditor.notebookOptions.getLayoutConfiguration().showFoldingControls;
		this.templateData.foldingIndicator.classList.remove('mouseover', 'always');
		this.templateData.foldingIndicator.classList.add(showFoldingIcon);
	}