var popup_window;

function OpenPopupWindow(file, title, width, height, scrollbars)
{
   var x = (screen.availWidth-width)/2;
   var y = (screen.availHeight-height)/2;

   popup_window = window.open(file,title,"width=" + width + ",height=" + height + ",left=" + x +",top=" + y + ",fullscreen=no,channelmode=no,toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=" + scrollbars + ",resizable=no");
   popup_window.focus();
}