function checkGroup(mainPageName) {
  var id = 'sub_page_group_' + mainPageName;
  if ($(id).visible()) {
    $(id).hide();
  } else {
    var groups = $$('div.sub-page-group');
    for (var i = 0; i < groups.length; i++) {
      if (groups[i].id != id) {
        groups[i].hide();
      }
    } 
    $(id).show();
  }
}

function clearForm(form_handle) {
  for (var i = 0; i < form_handle.elements.length; i++) {
    var element = form_handle.elements[i];
    var type = element.type;
    var tag = element.tagName.toLowerCase();
    if (type == 'text' || tag == 'textarea') {
      element.value = "";
    } else if (type == 'checkbox' || type == 'radio') {
      element.checked = false;
    } else if (tag == 'select') {
      element.selectedIndex = -1;
    }

  }
}