function popup(mylink, windowname, windowwidth, windowheight)
{
if (! window.focus)return true;
var href;
var openstring = 'width='+windowwidth
openstring += ',height='+windowheight
openstring += ', scrollbars=no, resizable=no'

if (typeof(mylink) == 'string')
   href=mylink;
else
   href=mylink.href;
window.open(href, windowname, openstring);
return false;
}