src/vs/base/browser/ui/list/listView.ts/ListView/updateWidth
class ListView:	updateWidth(index: number): void {
		if (!this.horizontalScrolling || typeof this.scrollWidth === 'undefined') {
			return;
		}

		const item = this.items[index];
		this.measureItemWidth(item);

		if (typeof item.width !== 'undefined' && item.width > this.scrollWidth) {
			this.scrollWidth = item.width;
			this.scrollableElement.setScrollDimensions({ scrollWidth: this.scrollWidth + 10 });
		}
	}