var obj;
var xPos = 0;
var yPos = 0;
var oldObj;

function roll(objId) {
	oldObj = objId;
	xPos = 0;
	yPos = 0;
	obj = document.getElementById(objId);
    while (obj) {
      xPos += obj.offsetLeft;
      yPos += obj.offsetTop;
      obj = obj.offsetParent;
    }
	xPos = xPos + "px";
	yPos = yPos + "px";

	document.getElementById(objId).className='no';
	
	document.getElementById(objId + "roll").className='vis';
	document.getElementById(objId + "roll").style.left = xPos;
	document.getElementById(objId + "roll").style.top = yPos;
}

function hide() {
	document.getElementById(oldObj + "roll").className='hid';
}