По поводу маски

[DarkLight]

function drawRect(mc:MovieClip, a:Number, b:Number):Void {
	mc.moveTo(a, a);
	mc.lineTo(b, a);
	mc.lineTo(b, b);
	mc.lineTo(a, b);
	mc.lineTo(a, a);
}
function drawBorder(mc:MovieClip):Void {
	mc.beginFill(0);
	mc.lineStyle(1, 0);
	drawRect(mc, 0, 100);
	drawRect(mc, 10, 90);
	mc.endFill();
}
_root.createEmptyMovieClip("brd", 1);
brd._x = 100;
brd._y = 100;
drawBorder(brd);