src/vs/editor/common/viewModel/overviewZoneManager.ts/OverviewRulerZone/compare
class OverviewRulerZone:	public static compare(a: OverviewRulerZone, b: OverviewRulerZone): number {
		if (a.color === b.color) {
			if (a.startLineNumber === b.startLineNumber) {
				if (a.heightInLines === b.heightInLines) {
					return a.endLineNumber - b.endLineNumber;
				}
				return a.heightInLines - b.heightInLines;
			}
			return a.startLineNumber - b.startLineNumber;
		}
		return a.color < b.color ? -1 : 1;
	}