Error 1131: Classes Must Not Be Nested

Question

I'm using Flash CS4 Professional to build a draggable element. However, whenever I input my code, I get error 1131. Can somebody please tell me what I'm doing wrong?

stop();

class Scrollbar extends Sprite
{
    var value:Number;
    var padding:Number = 5;

    var _textField:TextField;
    var max:Number;
    var min:Number;
    function draggable()
    {
        min = bar_mc.y;
        max = bar_mc.height - Erhu_H3_btn.height;
        Erhu_H3_btn.addEventListener(MouseEvent.MOUSE_DOWN, dragHandle);
    }

    function dragHandle(event:MouseEvent):void
    {
        Erhu_H3_btn.startDrag(false, new Rectangle(0,min,0,max));
        stage.addEventListener(MouseEvent.MOUSE_UP, stopDragging);
    }

    function stopDragging(event:MouseEvent):void
    {
        Erhu_H3_btn.stopDrag();
        stage.removeEventListener(MouseEvent.MOUSE_UP, stopDragging);
    }

}

Answer 1

You should put the codes of Scrollbar class in a separate .as file and then you can declare an instance like this:

import PackageName.Scrollbar;
stop();
var scrollbar:Scrollbar = new Scrollbar();

Scrollbar class located in "PackageName\Scrollbar.as":

package PackageName{
    import flash.display.Sprite;
    public class Scrollbar extends Sprite{
         var value:Number;
         //...
    }

}