function verzenden() {
	var goed = 0;
	if(document.quiz.vraag[0].checked != false) {
		goed++;
	} 
	
	if(document.quiz.vraag[1].checked != false) {
		goed++;
	} 
	
	if(document.quiz.vraag[2].checked != false) {
		goed++;
	} 
	
	if(document.quiz.vraag[3].checked != false) {
		goed++;
	} 
	
	if(goed > 0) {
		return true;
	} else {
		return false;	
	}
}
function changeLayerVisibility(layerID, layerState)
	{
		if(document.layers) //NN4+
	    {
			document.layers[layerID].display = layerState ? layerState : (document.layers[layerID].display == "block" ? "none" : "block");
	    }
	    else if(document.getElementById) //gecko(NN6) + IE 5+
	    {
	        var obj = document.getElementById(layerID);
	    	obj.style.display = layerState ? layerState : (obj.style.display == "block" ? "none" : "block");
	    }
	    else if(document.all) // IE 4
	    {
	    	document.all[layerID].style.display = layerState ? layerState : (document.all[layerID].style.display == "block" ? "none" : "block");
	    }
	}