<!--
function alpha(opacity){
	if(opacity == 0){
	   document.getElementById('titel').style.visibility = 'hidden';
	   document.getElementById('scrollbar_track').style.visibility = 'hidden';
	   document.getElementById('scrollbar_handle').style.visibility = 'hidden';
	   document.getElementById('content').style.visibility = 'hidden';
	   document.getElementById('content_2').style.visibility = 'hidden';
	   document.getElementById('holder').style.visibility = 'hidden';
           document.getElementById('sluiten').style.visibility = 'hidden';
           document.getElementById('open').style.visibility = 'visible';
	} else {
	   document.getElementById('titel').style.visibility = 'visible';
	   document.getElementById('scrollbar_track').style.visibility = 'visible';
	   document.getElementById('scrollbar_handle').style.visibility = 'visible';
	   document.getElementById('content').style.visibility = 'visible';
	   document.getElementById('content_2').style.visibility = 'visible';
	   document.getElementById('holder').style.visibility = 'visible';
           document.getElementById('sluiten').style.visibility = 'visible';
           document.getElementById('open').style.visibility = 'hidden';
	}
}
//-->