var newwindow = ''
function PopupPic(url) {
if (newwindow.location && !newwindow.closed) {
    newwindow.location.href = url; 
    newwindow.focus(); } 
else { 
    newwindow=window.open(url,'htmlname','width=792,height=594,resizable=0');} 
}

function tidy() {
if (newwindow.location && !newwindow.closed) { 
   newwindow.close(); } 
}