function changePreview2(tabNumber) {
  var tabNames = ['tab21','tab22','tab23','tab24'];
  for (i = 1; i <= tabNames.length; i++) {
        document.getElementById('tab-content-sect-2' + i).style.display = 'none';
      }
      document.getElementById('tab-content-sect-2' + tabNumber).style.display = 'block';
      lis = document.getElementById('tab-content-list2').getElementsByTagName('li');
      for (i = 0; i < lis.length; i++) {
        if (lis[i].className == 'active')
          lis[i].className = 'menu';
      }
      document.getElementById('tab2' + tabNumber).className = 'active';
      if (typeof urchinTracker == 'function') {
        urchinTracker('/sgaht-megrendelo/tab-2/' + tabNames[tabNumber - 1]);
      } else if (typeof pageTracker._trackPageview == 'function') {
        pageTracker._trackPageview('/sgaht-megrendelo/tab-2/' + tabNames[tabNumber - 1]);
      }
    }