Problem when using function in function as timer event handler

To implement a blinking effect of some button, one can use a timer with limited repeat count to flip the visible property in the timer event  and set back visible when timer complete, as follows:

import flash.utils.Timer;
import flash.events.TimerEvent; 

function doBLinkingButton():void 
{
    function handleTimer(e:TimerEvent):void 
    { 
        myButton.visible = !myButton.visible; 
    }

    function handleCompleteTimer(e:TimerEvent):void 
    { 
        myButton.visible = true;
    }

    // repeat timer 6 times with 0.5-second cycle 
    Timer tmr:Timer = new Timer(500, 6); 
    tmr.addEventListener(TimerEvent.TIMER, handleTimer); 
    tmr.addEventListener(TimerEvent.TIMER_COMPLETE,
handleCompleteTimer); 
}

Looking good, right?

If you run this code, you'll find for even-number times the handler executes, the flipping of visible properties won't succeed! The reason is because we are using a function in function as an event handler.

If you move handleTimer function outside doBLinkingButtion function to make it a class-level method, then the flipping will succeed each time handleTimer is called.