function PlaceNav(item){
document.write('');
}
function PlaceKaart(){
document.write('');
}
function pop_up(url,width,height) {
popwidth = width;
popheight = height;
window.open(url,"pop_up","width="+ popwidth +",height="+ popheight +",scrollbars=yes,toolbar=no,resizable=no," + align_string_pop(popwidth, popheight))
}
function align_string_pop(popwidth, popheight) {
var breedte = screen.width;
var hoogte = screen.height;
var prop_left = (screen.width/2) - (popwidth/2);
var prop_top = (screen.height/2) - (popheight/2);
return "left=" + prop_left + ",top=" + prop_top;
}