Addressing an element outside of the current class

I have setup a column layout like this:
file1.php loads up atk4, creates an $app and $layout.
Basically I’d like to reload the right column from the grid class of the left column after pressing a button of a modal window that opens within the grid.
Here’s the code:

class Overview extends \atk4\ui\Grid {
      public $reloadAfterSave;

      public function init(): void {

      public function setupGrid1($reloadAfterSave) {
          // Adding new entry button
         $addButton = $this->menu->addItem([t('Add_client'), 'icon' => 'add square']);

          // add a modal window to the grid for a new entry
          $this->modal = \atk4\ui\Modal::addTo($this->app, ['title' => t('New_entry')]);
          $newentryForm = \atk4\ui\Form::addTo($this->modal);

          // When button is clicked, show the modal
         $addButton->on('click', $this->modal->show());

         $newentryForm->onSubmit(function($form) {
               // Get submitted var
               global $reloadAfterSave;

               // form is saved first

              // This should load content into $right column
              $reload = new \atk4\ui\jsReload($reloadAfterSave, ['val'=> new \atk4\ui\jsExpression('[]', [new \atk4\ui\jsExpression('3')])]);

              // Close the modal window and send a success message
              return [
                  new \atk4\ui\JsToast(t('Successfully_saved')),
                  new \atk4\ui\JsReload($this)

    // Setup the columns
    $col = \atk4\ui\Columns::addTo($app);
    $left = $col->addColumn(6);
    $right = $col->addColumn(9);

    // Add time to right column to see when a change occurs
    \atk4\ui\Text::addTo($right, [date('YmdHis')]);  

    // adding a grid that's defined below
    $o = Overview::addTo($left);

I’m pressing the “New entry” button. The modal window opens. I’m entering some data and click “Save”. The modal closes and the right column doesn’t reload.

What is wrong here?