Flex is driving me CRAZY and I think it's some weird gotcha with how it handles leap years and none leap years. So here's my example. I have the below dateDiff method that finds the number of days or milliseconds between two dates. If I run the following three statements I get some weird issues.

    	dateDiff("date", new Date(2010, 0,1), new Date(2010, 0, 31));
	dateDiff("date", new Date(2010, 1,1), new Date(2010, 1, 28));
	dateDiff("date", new Date(2010, 2,1), new Date(2010, 2, 31));
	dateDiff("date", new Date(2010, 3,1), new Date(2010, 3, 30));

If you were to look at the date comparisons above you would expect to get 30, 27, 30, 29 as the number of days between the dates. There weird part is that I get 29 when comparing March 1 to March 31. Why is that? Is it something to do with February only having 28 days? If anyone has ANY input on this that would be greatly appreciated.

public static function dateDiff( datePart:String, startDate:Date, endDate:Date ):Number 
	{
		var _returnValue:Number = 0;

		switch (datePart) {
			case "milliseconds":
				_returnValue = endDate.time - startDate.time;
				break;
			case "date":
				// TODO: Need to figure out DST problem i.e. 23 hours at DST start, 25 at end.
				// Math.floor causes rounding down error with DST start at dayOfYear
				_returnValue = Math.floor(dateDiff("milliseconds", startDate, endDate)/(1000 * 60 * 60 * 24));
				break;
		}

		return _returnValue;
	}