var act;
var w;
act=0;
var size='300';
var p1,p2;
var obj1, obj2;

function init(){
	w=document.getElementById('window').getElementsByTagName('DIV');
	for (var n=0;n<w.length;n++){
		w[n].style.top=size+'px';
		w[n].style.position='absolute';
		w[n].style.zindex=n;
		}
	w[act].style.top='0px';
	
}


function up(){
	
	if (act<(w.length-1)){		
		obj1=w[act];
		p1=0;
		act=act+1;
		obj2=w[act];
		p2=300;
		timer=setInterval ('movement()',10);
	
		}
	}


function down(){
	if (act>0){	
		obj1=w[act];
		p1=0;
		act=act-1;
		obj2=w[act];
		p2=300;
		timer=setInterval ('movement()',10);
		}
	}

function movement(){
p1=p1+10;
p2=p2-10;
obj1.style.top=p1+'px';
obj2.style.top=p2+'px';
if (p2==0)clearInterval(timer) ;
}