function fly_airplane() {
pos=announce_box.style.left;
alt=announce_box.style.top;
newpos=parseInt(pos)+2;
newalt=parseInt(alt)+Math.round(Math.random()*2)-1;
if (newpos>rootdivwidth+50) {
	newpos=-parseInt(announce_box.style.width);
	window.clearInterval(airplane_motion);
	}
announce_box.style.left=newpos;
announce_box.style.top=newalt;
}

function init() {
announce_box=eval(prefix+"announce"+suffix);
window_box=eval(prefix+"window"+suffix);
rootdivwidth=parseInt(window_box.style.width);
}

function start_airplane(n) {
airplane_height=Math.round(Math.random()*200)+100;
announce_box.style.top=airplane_height;
airplane_motion=window.setInterval("fly_airplane()",n);
}