code: function handleSelectedIndexChange (newValue, oldValue) {
      if (newValue === oldValue) return;
  
      ctrl.selectedIndex     = getNearestSafeIndex(newValue);
      ctrl.lastSelectedIndex = oldValue;
      ctrl.updateInkBarStyles();
      updateHeightFromContent();
      adjustOffset(newValue);
      $scope.$broadcast('$mdTabsChanged');
      ctrl.tabs[ oldValue ] && ctrl.tabs[ oldValue ].scope.deselect();
      ctrl.tabs[ newValue ] && ctrl.tabs[ newValue ].scope.select();
    }
docs: Update the UI whenever the selected index changes. Calls user-defined select/deselect methods.
  @param {number} newValue selected index's new value
  @param {number} oldValue selected index's previous value