function gradient(id, level)
{
	var box = document.getElementById(id);
	box.style.opacity = level;
	box.style.MozOpacity = level;
	box.style.KhtmlOpacity = level;
	box.style.filter = "alpha(opacity=" + level * 100 + ")";
	box.style.display="block";
	return;
}


function fadein(id) 
{
	var level = 0;
	while(level <= 1)
	{
		setTimeout( "gradient('" + id + "'," + level + ")", (level* 1000) + 10);
		level += 0.01;
	}
}


// Open the lightbox


function openbox(formtitle, fadin)
{
  var box = document.getElementById('box'); 
  document.getElementById('filter').style.display='block';

  var btitle = document.getElementById('boxtitle');
  btitle.innerHTML = formtitle;
  
  if(fadin)
  {
	 gradient("box", 0);
	 fadein("box");
  }
  else
  { 	
    box.style.display='block';
  }  	
}


// Close the lightbox

function closebox()
{
   document.getElementById('box').style.display='none';
   document.getElementById('filter').style.display='none';
}

// Open the lightbox

function setCookie(c_name,value,expiredays)
{
var exdate=new Date();
exdate.setDate(exdate.getDate()+expiredays);
document.cookie=c_name+ "=" +escape(value)+
((expiredays==null) ? "" : ";expires="+exdate.toGMTString());
}

function getCookie(c_name)
{
if (document.cookie.length>0)
  {
  c_start=document.cookie.indexOf(c_name + "=");
  if (c_start!=-1)
    {
    c_start=c_start + c_name.length+1;
    c_end=document.cookie.indexOf(";",c_start);
    if (c_end==-1) c_end=document.cookie.length;
    return unescape(document.cookie.substring(c_start,c_end));
    }
  }
return "";
}

function checkCookie()
{
add=getCookie('add');
if (add!=null && add!="")
  {
    return false;
  }
else
  {
    openbox('Advertentie: Vakantiemogelijkheden', 0);
  }
}