function pop()
{
testwindow= window.open ("uslovi.php", "mywindow",
    "toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=Yes,resizable=no,copyhistory=no,width=400,height=300");

testwindow.moveTo(screen.availWidth/2-(400/2),screen.availHeight/2-(300/2));
}