setRGB problem

programming flash
1

Hi There - Every time I move the mouse, I want a movieClip attached to the stage from the library. Each time it hits the stage, I want it to be a random colour from the choice from my Array. Only the first movieClip to arrive - has the chance to be 'another colour, from the code below.

Any Tips on using the setRGB function??? It is that that seems tangled up in my code at the moment…

var a:Array = new Array("0x66FFFF","0x333333");
var ear:Object = new Object();
function line()
{
    num = Math.floor(Math.random()*2);   _root.attachMovie("square","square_mc",this.getNextHighestDepth());
    var colorful = new Color("line_mc");
    colorful.setRGB(a[num]);   
}
ear.onMouseMove = function(){ line(); };
Mouse.addListener(ear);

Thanks!