code: function getNavigationRoot(targetControl) {
          var navigationRoot, controls;
  
          targetControl = targetControl || focusedControl;
          controls = targetControl.parents().toArray();
          controls.unshift(targetControl);
  
          for (var i = 0; i < controls.length; i++) {
            navigationRoot = controls[i];
  
            if (navigationRoot.settings.ariaRoot) {
              break;
            }
          }
  
          return navigationRoot;
        }
docs: Returns the navigation root control for the specified control. The navigation root
  is the control that the keyboard navigation gets scoped to for example a menubar or toolbar group.
  It will look for parents of the specified target control or the currently focused control if this option is omitted.
  
  @private
  @param {tinymce.ui.Control} targetControl Optional target control to find root of.
  @return {tinymce.ui.Control} Navigation root control.