code: function focusFirst(targetControl) {
          var navigationRoot = getNavigationRoot(targetControl);
          var focusElements = getFocusElements(navigationRoot.getEl());
  
          if (navigationRoot.settings.ariaRemember && "lastAriaIndex" in navigationRoot) {
            moveFocusToIndex(navigationRoot.lastAriaIndex, focusElements);
          } else {
            moveFocusToIndex(0, focusElements);
          }
        }
docs: Focuses the first item in the specified targetControl element or the last aria index if the
  navigation root has the ariaRemember option enabled.
  
  @private
  @param {tinymce.ui.Control} targetControl Target control to focus the first item in.