src/vs/platform/list/browser/listService.ts/ListService/setLastFocusedList
class ListService:	private setLastFocusedList(widget: WorkbenchListWidget | undefined): void {
		if (widget === this._lastFocusedWidget) {
			return;
		}

		this._lastFocusedWidget?.getHTMLElement().classList.remove('last-focused');
		this._lastFocusedWidget = widget;
		this._lastFocusedWidget?.getHTMLElement().classList.add('last-focused');
	}