function mostrar(id,contenedor_img){
  var array_div=document.getElementsByClassName("detalleproducto","div");
  for(var i=0;i<array_div.length;i++){ocultar("pro"+i);}
  var div = document.getElementById(id);
  var cont = document.getElementById(contenedor_img);
  posicionx = getDimensions(cont).x;
  posiciony = getDimensions(cont).y;
  div.style.top=""+(posiciony)+"px";
  div.style.left=""+(posicionx)+"px";
  div.style.visibility = 'visible';
  return false;
}
function ocultar(id){
  try{
  document.getElementById(id).style.visibility = 'hidden';}
  catch(e){}
  return false;
}

document.getElementsByClassName = function(cl, sTagName) {  
	var retnode = [];  
	var myclass = new RegExp('\\b'+cl+'\\b');  
	var elem = this.getElementsByTagName((sTagName===""||sTagName===null)?"*":sTagName);  
	for (var i = 0; i < elem.length; i++) {  
		var classes = elem[i].className;  
		if (myclass.test(classes)) retnode.push(elem[i]);  
		}  
	return retnode;  
};  

getDimensions = function(oElement) {
var x, y, w, h;
x = y = w = h = 0;
if (document.getBoxObjectFor) { // Mozilla
var oBox = document.getBoxObjectFor(oElement);
x = oBox.x-1;
w = oBox.width;
y = oBox.y-1;
h = oBox.height;
}
else if (oElement.getBoundingClientRect) { // IE
var oRect = oElement.getBoundingClientRect();
x = oRect.left-2;
w = oElement.clientWidth;
y = oRect.top-2;
h = oElement.clientHeight;
}
return {x: x, y: y, w: w, h: h};
}