function MM_findObj(n, d) { //v3.0
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document); return x;
}
function MM_swapImage() { //v3.0
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
   if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}
function MM_swapImgRestore() { //v3.0
  var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}

function MM_preloadImages() { //v3.0
 var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
   var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
   if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}

function test_formcontacto(theForm)	{
	if ((theForm.Nombre.value == "") || (theForm.Email.value == "") || (theForm.Asunto.value == ""))	{
		alert("Por favor, asegurese de haber rellenado los campos marcados con astérisco.");
	}
	else	{
		theForm.action = "contacto.php";
		theForm.submit();
	}								
}

function test_formboletin(theForm)	{
	if ((theForm.Nombre.value == "") || (theForm.mail.value == ""))	{
		alert("Por favor, asegurese de haber rellenado los campos marcados con astérisco.");
	}
	else	{
		theForm.action = "boletin.php";
		theForm.submit();
	}								
}
<!----------ZOOM IMAGES------------------->
function openwindow(url,ancho,alto) {
	propiedades = "toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=0,resizable=0,width=" + ancho + ",height=" + alto + ",left=200,top=0";
	mywin = window.open(url,"win",propiedades);
	mywin.self.focus();
}