var s = "s"; //slider id
var sbg = "s-bg"; //slider background id

function objClass(obj,cl){ //change element class
	obj.className = cl;
}
function getY(obj){
	Y = 0;
	if (obj.offsetParent){
		do {Y += obj.offsetTop;} 
		while (obj = obj.offsetParent);
	}
	return Y;
}

var IE = document.all?true:false; //check if browser is IE
if (!IE) document.captureEvents(Event.MOUSEMOVE);
document.onmousemove = MouseY;
var mY = 0;
var mYsY = 0;
function MouseY(e){
	if (IE) mY = event.clientY + document.body.scrollTop;
	else mY = e.pageY;
	if (mYsY != 0) slide(1);
}
function mDown(obj){
	objClass(obj,'s-active');
	sY = getY($(s));
	mYsY = mY - sY;
}

function slide(m){
	bgY = getY($(sbg));
	sHeight = $(s).offsetHeight;
	bgHeight = $(sbg).offsetHeight;
	var Y = mY - bgY - sHeight / 2;
	if (m == 1) Y = mY - bgY - mYsY;
	if (Y < 0) Y = 0;
	if (Y > bgHeight - sHeight) Y = bgHeight - sHeight;
	$(s).style.marginTop = Y+"px";
	scroll(Y, bgHeight - sHeight);
}
function slideStop(){
	objClass($(s),'');
	mYsY = 0;
}
function mOut(obj){
	if(mYsY == 0) objClass($(s),'');
}
function mOver(obj){
	if(mYsY == 0) objClass($(s),'s-hover');
}