function tabsheetActivate(sender, sheetId) {
  var senderTab = sender.parentNode;
  var tabsheetTabs = senderTab.parentNode;
  for (var tab = tabsheetTabs.firstChild; tab; tab = tab.nextSibling) {
    if (tab.nodeType == 1) { // it is element
      if (tab != senderTab) {
        tab.className = "";
      } else {
        tab.className = "active";
      }
    }
  }

  var tabsheetSheets = tabsheetTabs;
  do {
    tabsheetSheets = tabsheetSheets.nextSibling;
  } while (tabsheetSheets && tabsheetSheets.nodeType != 1);

  for (var sheet = tabsheetSheets.firstChild; sheet; sheet = sheet.nextSibling) {
    if (sheet.nodeType == 1) { // it is element
      if (sheet.getAttribute("id") != sheetId) {
        sheet.className = "tabsheet-sheet-invisible";
      } else {
        sheet.className = "tabsheet-sheet-visible";
      }
    }
  }

  return false;
}