var pop = null; 
function popdown() 
{ 
if (pop && !pop.closed) pop.close(); 
} 
function popup(obj,w,h)
{ 
var url = (obj.getAttribute) ? obj.getAttribute('href') : obj.href; 
if (!url) return true; 
w = (w) ? w += 20 : 150; // 150px*150px is the default size h = (h) ? h += 25 : 150; 
var args = 'width='+w+',height='+h+',resizable'; 
popdown(); 
pop = window.open(url,'',args); 
return (pop) ? false : true; 
}
window.onunload = popdown; window.onfocus = popdown;