Why are my numeric stepper values so far out past the decimal point?

Question

I'm using the Flex 4.6 Spark Numeric Stepper in my app and when I enter .9 it returns, "0.9000000953674316". I can enter any value actually. It is doing it for all of them.

If I use the arrow buttons it moves from 0 to 1 it sets the value to "0.09999990463256836".

UPDATE:
So running more tests. If I start and zero and then go down it's:

0
-0.1
-0.2
-0.30000000000000004
-0.4

and if I then go back up it's:

-0.30000000000000004
-0.20000000000000004
-0.10000000000000003
-2.7755575615628914e-17
NaN

Here is my formatter code:

precision = 100;
public function formatNumericStepper(value:Number):String {
    return String(int(value*precision)/precision);
}

Note: Sometimes the value gets stuck at -.7 or .28. It works fine for whole numbers but it's buggy as heck with numbers less than one. Or I'm doing something wrong.

Answer 1

With some finessing and helpful direction from @DodgerThud the following seems to be working:

MXML:

<s:NumericStepper id="numericStepper" snapInterval="0" stepSize=".01"
                  valueFormatFunction="formatNumericStepper"
                  valueParseFunction="valueParseFunctionNew"/>

ACTIONSCRIPT:

public var precision:int = 100;

public var fixedPosition:int = 2;

/**
 * Format numeric stepper
 * Trim down to 2 decimal places.
 * */
public function formatNumericStepper(value:Number):String {
    var out:String;
    if (fixedPosition!=0) {
        out = Number(value.toFixed(fixedPosition)).toString();
    }
    else {
        out = String(int(value * precision) / precision);
    }
    return out;
}


public function valueParseFunction(value:String):Number {
    var out:Number;
    if (fixedPosition!=0) {
        out = Number(Number(value).toFixed(fixedPosition));
    }
    else {
        out = Number(value);
    }
    return out;
}

I think it was getting stuck because if you have a small enough step size, say .1 and then you are rounding using value*100/100 you are sometimes rounding down. Therefore, it is never a large or small enough step to get past a certain value.

The else statements could probably be removed. I kept them in so if it's possible to do it dynamically I can use the step size to get the decimal position as a counter.

So if step size is .1 then fixedPosition would be 1. If step size is .01 then fixedPosition would be 2. If .001 or .999 then the fixed position would be 3.