ActionScript 3.0 :: Initialize Movieclip's Width Value Only Once?

setting a rectangle movieclip instance's width to 20 at the very start, before the ENTER_FRAME function is fired, but the width remains 20 throughout. I've tried different methods, here are two examples.Here's a simplified, short example:

Actionscript Code:
var rect_mcW:Number = rect_mc.width; //store original widthrect_mc.width = 20; //then set the rectangle's width to 20rect_mc.addEventListener(Event.ENTER_FRAME, growRect);function

[code]....

Ok, so the rect_mc's width remains 20 for each ENTER_FRAME event, even though the event listener function should grow it, but doesn't.One other way I tried was wrapping the 20 width inside a function:

Actionscript Code:
// opening statements omitted for brevity//first call to addEventListener:rect_mc.addEventListener(Event.ENTER_FRAME, init_width); //on first

[code]....

this second example yields the same result, the rect_mc width remains 20 even Though I thought the event listener that calls the function that sets it to 20 is removed first thing in the second event listener.

So, I assume it's because the code is read from top, and the code that sets width to 20 gets read and executed over and over. But still, shouldn't the growing part also take place over and over? What I want obviously is to store the original width, but start the animation with a width of 20, but just once.