Position of buttons as3

Question

I need some help with Positions of buttons in AS3. I made a IRC client with AS3, but when a user join a channel, there will be a button added, but if there is already a button and the user join new channel on IRC, there will be added new button also, this for every channel that a user does join, but It should to be positioned after the last button (side by side). Same for if a user join more channels. How can i do this on best way with x and y positions? Ofcourse, it must check first if there is already button on the position if a user did join channel.
This is my code for now:
const PADDING:uint = 10;
const NUM_BUTTONS:uint = 10;
onChannelButton();
function onChannelButton():void {
    var test:Sprite = new Sprite();
    var btn:Button;
    //NUM_BUTTONS or btn.length ?
    for (var i:int = 0; i < NUM_BUTTONS; i++)
            btn = new Button();
            btn.name = "btn";
            btn.width = 90;
            btn.x = (btn.width + PADDING) * i;
            test.addChild(btn);
    addChild(test);
Example how to do: http://oi42.tinypic.com/j5cl0i.jpg
Thanks!

Answer 1

var btn_parent:Spirte=new Sprite();
btn_parent.name="btn_parent";
MovieClip(root).addChild(btn_parent);
// whenever you add a btn:
const COLNUM:int = 25;
const PADDING:uint = 10;
const NUM_BUTTONS:uint = 10;
onChannelButton();
function onChannelButton():void {
    var btn:Button;
    //NUM_BUTTONS or btn.length ?
    for (var i:int = 0; i < NUM_BUTTONS; i++)
            btn = new Button();
            btn.name = "btn";
            btn.width = 90;
positionF(btn);
           btn_parent.addChild(btn);
function positionF(btn:Button):void{
btn.x = (btn_parent.numChildren%COLNUM)*(btn.width+PADDING));
btn.y = Math.floor(btn_parent.numChildren/COLNUM)*(btn.height+PADDING);