function popup(mylink, windowname,popwidth,popheight)
{
if (! window.focus)return true;
var href;
if (typeof(mylink) == 'string')
   href=mylink;
else
   href=mylink.href;
window.open(href, windowname, 'width='+popwidth+',height='+popheight+',resizable=no');
return false;
}