var change		= 1000;
var pos			= 0;
var s			= 3000;
var mySlide		= '';

function startSlide(){
	try{
		s = parseInt(document.getElementById('contenu').scrollHeight-37);
		if(isNaN(s))
			s = 3000;
	}
	catch (error){
		s = 3000;
	}
	change = Math.round(s/110);
	mySlide = new Slider($('slider_fond'), $('slider_slider'), {	
		steps:s,
		mode: 'vertical',	
		onChange: function(step){
			pos = step;
			document.getElementById('contenu').style.marginTop = -1*step+'px';
		}
	}).set(0);
	document.addEvent('mousewheel', function(event) {
		event = new Event(event);
		if (event.wheel > 0)
			newsUp();
		else if (event.wheel < 0)
			newsDown();
	});
}
function newsUp(){
	pos -= change;
	if(pos<0)
		pos = 0;
	mySlide.set(pos);
}
function newsDown(){
	pos += change;
	if(pos>document.getElementById('contenu').scrollHeight-37)
		pos = document.getElementById('contenu').scrollHeight-37;
	mySlide.set(pos);
}
window.addEvent('domready', function(){
	startSlide();
});