function OpenPopup(a) {
  
  var feedback_window = {
            width: 760,
            height: 570,
            left: function() {return Math.ceil((screen.availWidth - this.width)/2)},
            top: function() {return Math.ceil((screen.availHeight - this.height)/2)},
            open: function(href) {
              
              window.open(href, 'o' + href.replace(/([^0-9]+)([0-9]+)(.+)/, '$2'), 'scrollbars=yes,width='+this.width+',height='+this.height+',left='+this.left()+',top='+this.top()+',resizable=0,toolbar=0,location=0,status=0,menubar=0,directories=0');
            }
  };
  
  feedback_window.open(a.href);
  
  return false;
}