src/vs/base/browser/ui/list/listWidget.ts/List/findPreviousIndex
class List:	private findPreviousIndex(index: number, loop = false, filter?: (element: T) => boolean): number {
		for (let i = 0; i < this.length; i++) {
			if (index < 0 && !loop) {
				return -1;
			}

			index = (this.length + (index % this.length)) % this.length;

			if (!filter || filter(this.element(index))) {
				return index;
			}

			index--;
		}

		return -1;
	}