admin/config/development/configuration/single/export doesn't allow you to export a single configuration.

I see UI elements getting repeated in other parts of admin as well, looks like this is a more general issue.

I noticed it in https://www.drupal.org/node/1997692#comment-9389129, where drag/drop causes submit buttons to duplicate.

Also, in views, when creating a new view, filling out the path for a new page, when that field loses focus it duplicates parts of the interface:

I would assume that this is related to #2384545: $element['#ajax']['callback'] is broken, hence breaking e.g. inserting images in CKEditor. Not sure if it is a duplicate, as it should still work without #ajax?

Confirming that this is a duplicate of #2384545: $element['#ajax']['callback'] is broken, hence breaking e.g. inserting images in CKEditor.

From \Drupal\config\Form\ConfigSingleExportForm:

    $form['config_type'] = array(
      '#title' => $this->t('Configuration type'),
      '#type' => 'select',
      '#options' => $config_types,
      '#default_value' => $config_type,
      '#ajax' => array(
        'callback' => '::updateConfigurationType',
        'wrapper' => 'edit-config-type-wrapper',
      ),
    );
    $default_type = $form_state->getValue('config_type', $config_type);
    $form['config_name'] = array(
      '#title' => $this->t('Configuration name'),
      '#type' => 'select',
      '#options' => $this->findConfiguration($default_type),
      '#default_value' => $config_name,
      '#required' => TRUE,
      '#prefix' => '<div id="edit-config-type-wrapper">',
      '#suffix' => '</div>',
      '#ajax' => array(
        'callback' => '::updateExport',
        'wrapper' => 'edit-export-wrapper',
      ),
    );

Not sure if it is a duplicate, as it should still work without #ajax?

It's not designed to work that way:

  public function submitForm(array &$form, FormStateInterface $form_state) {
    // Nothing to submit.
  }

Is it a bug that it doesn't work with JS disabled completely? I forget what our policy is for that (it is administration, not end-user facing)