function openWin(src){
 lt=(window.screen.width/2)-400;
 tp=(window.screen.height/2)-300;
 var win=window.open("/show_screen.php?src="+src,"","status=no,scrollbars=yes,location=no,menubar=no,resizable=yes, toolbar=no, width=850, height=650, left="+lt+", top="+tp);
 win.focus();
}