var ns4 = (document.layers);
var ie4 = (document.all && !document.getElementById);
var ie5 = (document.all && document.getElementById);
var ns6 = (!document.all && document.getElementById);


if (document.images)
{
  preload_image_object = new Image();
  
  image_url = new Array();
  image_url[0] = "images/main_grijs.jpg";
  image_url[1] = "images/main_oranje.jpg";
   var i = 0;
   for(i=0; i<=1; i++) 
     preload_image_object.src = image_url[i];
}
  
function show(id){
	// Netscape 4
	if(ns4){
		document.layers[id].visibility = "show";
	}
	// Explorer 4
	else if(ie4){
		document.all[id].style.visibility = "visible";
	}
	// W3C - Explorer 5+ and Netscape 6+
	else if(ie5 || ns6){
		document.getElementById(id).style.visibility = "visible";
	}
}

function hide(id){
	// Netscape 4
	if(ns4){
		document.layers[id].visibility = "hide";
	}
	// Explorer 4
	else if(ie4){
		document.all[id].style.visibility = "hidden";
	}
	// W3C - Explorer 5+ and Netscape 6+
	else if(ie5 || ns6){
		document.getElementById(id).style.visibility = "hidden";
	}
}

function openNewWindow(varpagename) {
	var MaxX = (this.screen.availWidth - 10);
	var MaxY = (this.screen.availHeight - 10);
	popupWin = window.open(varpagename, 'open_window', 'menubar=yes, toolbar=yes, location=yes, directories=yes, status=yes, scrollbars=yes, resizable=yes, dependent=no, width='+MaxX+', height='+MaxY+', left=0, top=0')
}