// Constants
var WIDTH = 50;
var HEIGHT = 20;
var yPos = 0;
var xPos = 0;
var counter = 0;

function start(){
    setTimer(draw, 1);
}

function draw(){
    var rect = new Rectangle(WIDTH, HEIGHT);
    rect.setPosition(xPos, yPos);
    rect.setColor(Color.randomRed());
    counter++;
    add(rect);
    xPos += HEIGHT;

    if (xPos > getWidth()) {
        xPos = HEIGHT;
        yPos += HEIGHT;
    }

    if (yPos > getHeight()) {
        stopTimer(draw);
    }
}