function externalLinks() {
 if (!document.getElementsByTagName) return;
 var anchors = document.getElementsByTagName("a");
 for (var i=0; i<anchors.length; i++) {
   var anchor = anchors[i];
   if (anchor.getAttribute("href") &&
       anchor.getAttribute("rel") == "external")
       anchor.target = "_blank";
 }
}

function changeClass(en,cn) {
if(!document.getElementById) return;
var element = document.getElementById(en);	
	element.className = cn;
}

function formValidation(form){
var radios = new Array();
var active = new Array();

		var test = "";
		for (var i = 0; i < form.elements.length; i++)
		{
    		var f = form.elements[i];
			
			if(f.type == 'radio') {
				if(f.name) var nr = f.name.substring(8,10);
			
				if (f.type == 'radio' && f.checked) var v = f.value;
				else var v = 0;
				if(!radios[nr - 1]) radios.push(nr);
				if(v != 0) active.push(nr);
			}
		}

		if(radios.length != active.length)
		{
			var def = radios.length - active.length;
			
			errors = "U heeft " + def + " van de " + radios.length +" vragen nog niet ingevuld:\n";
			errors += "Klik op [OK] om de vragen alsnog te beantwoorden. \n";
			
			alert(errors);
			return false;
		}else{
			return true;
		}		
}


function findPos(objName)
{
	var obj = document.getElementById(objName);
	var curleft = curtop = 0;
	if (obj.offsetParent) {
		curleft = obj.offsetLeft
		curtop = obj.offsetTop
		while (obj = obj.offsetParent) {
			curleft += obj.offsetLeft
			curtop += obj.offsetTop
		}
	}
	return [curleft,curtop];
}


window.onload = function(){ 
	externalLinks();
	
	var browser_app 		= navigator;
	var browser_app_version	= navigator.appVersion;
	var is_ie7				= browser_app_version.indexOf("MSIE 7");

	if(findPos('billboard_img')[0] > 41 && is_ie7 > -1) {
		history.go();
	};
}