Code snippet -- "Send to Back"?

Question

Hello,
I've modified the code snippet "Bring Object to the Front" to bring a given stage symbol to the front on mouse over. My question is, what code do I add to make the symbol go to the back on mouse out? My code is below -- exact same as the code snippet in CS5, but with MOUSE_OVER in place of CLICK. Many thanks!
// This code makes all symbol instances on stage clickable by making them listen for the CLICK event.
for (var fl_ChildIndex:int = 0;
        fl_ChildIndex < this.numChildren;
        fl_ChildIndex++)
    this.getChildAt(fl_ChildIndex).addEventListener(MouseEvent.MOUSE_OVER, fl_OverToBringToFront);
// This is the function that moves the over object to the front of the display list
function fl_OverToBringToFront(event:MouseEvent):void
    this.addChild(event.currentTarget as DisplayObject);

Answer 1

Thanks -- it's getting there but the behavior is weird and I'm getting an error message "TypeError: Error #1009: Cannot access a property or method of a null object reference.at transitshell_fla::lvbutton_5/fl_FadeSymbolIn()"
My code looks like this:
// This code makes all symbol instances on stage clickable by making them listen for the CLICK event.
for (var fl_ChildIndex:int = 0;
        fl_ChildIndex < this.numChildren;
        fl_ChildIndex++)
    this.getChildAt(fl_ChildIndex).addEventListener(MouseEvent.MOUSE_OVER, fl_OverToBringToFront);
    this.getChildAt(fl_ChildIndex).addEventListener(MouseEvent.MOUSE_OUT, fl_OverToSendToBack);
// This is the function that moves the over object to the front of the display list
function fl_OverToBringToFront(event:MouseEvent):void
    this.addChild(event.currentTarget as DisplayObject);
    function fl_OverToSendToBack(event:MouseEvent):void
    this.addChildAt(event.currentTarget as DisplayObject, 0);
Thanks for your help!