このまま実用はキツイけど、参考にしてみて下され。

class MyWindow extends Window
{
var primLayer, timer, i = 0;
function MyWindow()
{
super.Window(...);
this.borderStyle = bsSingle;
primLayer = new Layer(this, null);
primLayer.setSize(this.innerWidth, this.innerHeight);
this.visible = true;
}
function finalize()
{
invalidate timer if timer !== void;
super.finalize(...);
}
function onTimer()
{
var x = i % 10 * 20;
var y = i \ 10 * 20;
primLayer.drawText(x, y, i++, 0x000000, 255);
timer.enabled = false if y > window.innerHeight;
}
}
var window = new MyWindow();
with(window){
.timer = new Timer(.onTimer, '');
.timer.interval = 100;
.timer.enabled = true;
}