var inc;
var difH;
var speed = 20;
var interval;
var ft;
var step = 1;

function getd(v) { return document.getElementById(v); }
function shw_l(d) { d.style.visibility = "visible"; }
function hid_l(d) { d.style.visibility = "hidden"; }

function initarea(wdone) {
ft = 0;
upc = getd('upw');
dwc = getd('dww');
inc = getd('cin');
oct = getd('cot');
difH = inc.offsetHeight - oct.offsetHeight;

if (wdone) { wdone(); }
}

function Mmov(pr, ev){
	inc.style.marginTop = pr + 'px'; 
	interval = setTimeout(ev, speed);
}

function Mgiu(){
	clearTimeout(interval);
	if( difH > Math.abs(ft) ){
	ft -= step; 
	} else {
	ft = 0; 
	}	
    Mmov(ft, 'Mgiu()');
}

function Msu(){
	if( ft < 0 ) {
	ft += step; 
	Mmov(ft, 'Msu()');
}}

function Malt() {
    if (interval) clearTimeout(interval);
}