function popup(mylink, windowname, winwidth, winheight)
{
if (! window.focus)return true;
var href;
var window_setup;
this.window_setup="resizable,scrollbars=yes, width=" + winwidth + ",height=" + winheight;
if (typeof(mylink) == 'string')
   href=mylink;
else
   href=mylink.href;
window.open(href, windowname, this.window_setup); 
return false;
}