src/vs/workbench/contrib/files/browser/views/explorerViewer.ts/CompressedNavigationController/setIndex
class CompressedNavigationController:	setIndex(index: number): void {
		if (index < 0 || index >= this.items.length) {
			return;
		}

		this.labels[this._index].classList.remove('active');
		this._index = index;
		this.labels[this._index].classList.add('active');

		this._onDidChange.fire();
	}