팝업 가운데로 오픈

function movePopCenter()
{
 if ( document.layers )
 {
  var left_pos = screen.width / 2 - outerWidth / 2;
  var top_pos  = screen.height / 2 - outerHeight / 2;
 }
 else
 {
  var left_pos = screen.width / 2 - document.body.offsetWidth / 2;
  var top_pos  = -75 + screen.height / 2 - document.body.offsetHeight / 2;
 }
 self.moveTo(left_pos, top_pos);
}

opener.focus();
window.onLoad = movePopCenter;