_root replacement for AS3 for object referencing


I am having some problems with accessing objects on the main timeline.

I am calling this function registerMenuButtons() from a function getDimensions() in AS3:

function getDimensions():void {

and registerMenuButtons accesses a textfield in a movieclip on the main timeline:

function registerMenuButtons():void {
graphics_gr.start_txt.text = “start”
however it seems to be a null object reference, text does not change.

In AS 2 I would have used _root to reference graphics_gr.start_txt.text. However I understand that it does not exist anymore. So I defined a variable called ref = this.root, and when I trace ref.graphics_gr it gives me "[object] point1. However this does not apply for start_txt, and instead when i try ref.graphics_gr.start_txt it gives me a null reference.

Is there any way to use a similar method like _root in AS2 to access an MC? Really don’t know what’s the problem, and I am not using any custom Document Class at the moment. Thanks!