Flex Builder: How to access stage instances created in Flash CS3?

One issue is that this line:

public var myinstancename_mc: MovieClip;

only declares the variable, but your variable is still empty.  You have to assign it to something like a new movie clip or an existing one before you can set any properties on it.

you could do:

public var myinstancename_mc:MovieClip  = new MovieClip();

but I don't know if that's what you're going for.

Sorry I'm new to Flash and FlexBuilder, not even sure how to explain it.
I think this is the steps
1. Create a TextField or import an image to Stage
2. Convert it to Symbol
3. Give the instance a name in the Properties, eg. myObject_mc

Now, in the code (.as file in FlexBuilder) I want to do something like
myObject_mc.x = 10;

But it doesn't recognise myObject_mc

How to solve this problem?
Thanks ugeb and ngiamoris

Sorry I tried what I just said and it actually works, sorry I don't understand this thing.
Ok this is what I need to be done.

I need to create a symbol, which is a number inside a box, in Flash CS3.

So I created a box, called SymbolBox, and put it in another symbol, called MySymbol
I added a TextField into MySymbol.
So now MySymbol contains a SymbolBox (called box_mc), and a TextField (called txt).

In FlexBuilder, I need to change the text, I can do that by doing

public var mybox_mc: MovieClip;
mybox_mc.txt.text = "new text";

BUT I cannot access this

mybox_mc.box_mc

How do I change the color of the box?

I hope it's clear.. thank you guys

Actually, what I need is a text inside a box, where the text can change and the box color can change and I need to do the code in Flex Builder (.as file).
How do you do that? Thanks!

Ok I can do this

var box: MovieClip = MovieClip(numbox_mc.getChildByName("box"));

Now how do I change its color? (eg. to Blue)

Sorry but I couldn't edit my posts ^^;

> Are you building the app in flash and using AS classes from Flex?
That's right!

I think I have tried "Export to ActionScript" but I still couldn't solve the problem.
I'm really new to this... I might miss something obvious...

Sorry if I wasn't clear of what I need to do, here is what I need:
A number of blue boxes, with text inside them, dynamically created.
Each of the box will change color from blue to gray on mouse hover.
Thats it. But it needs to be done in an existing project, that consists of an .fla file (the Flash CS3 file) and the .as file (the FlexBuilder code)

I'm gonna go to the office and check ColorTransform in about 2 hours.
Thanks ugeb!

ugeb, thanks, the colorTransform works!! Thanks a lot!
Do you also know how to make the cursor change to hand on roll over? (instead of the text cursor)
Tried this but didnt work
                  numbox_mc.buttonMode = true;
                  numbox_mc.mouseEnabled = true;