Flex中2个补间动画之间的无限循环

<fx:Declarations>
    <s:Animate id=\"goRight\"
        duration=\"3000\" target=\"{nShape}\" >
        <s:SimpleMotionPath property=\"x\" valueFrom=\"0\" valueTo=\"400\" />
    </s:Animate>
</fx:Declarations>

var animate:Boolean = true;
var isLeft:Boolean = true;

while (animate)
{
    if (isLeft) 
    {
        goRight.play(null);
        while (goRight.isPlaying){};
    }
    else {
        goRight.play(null, true); // play it backwards
        while (goRight.isPlaying){};
    }

    isLeft = !isLeft;
}