[Joost]

Stylesheet's for alternative tooltip theme's are not loaded.
Following code change enables them:

EDIT ext.tooltipster.php:

 // function to publish and register assets on page 
  public function publishAssets() {
    $assets = dirname(__FILE__) . '/assets';
    $baseUrl = Yii::app()->assetManager->publish($assets);

    if (is_dir($assets)) {
      Yii::app()->clientScript->registerCoreScript('jquery');
      Yii::app()->clientScript->registerCssFile($baseUrl . '/css/tooltipster.css');

ADD these lines to enable theme's

      Yii::app()->clientScript->registerCssFile($baseUrl . '/css/themes/tooltipster-shadow.css');
      Yii::app()->clientScript->registerCssFile($baseUrl . '/css/themes/tooltipster-noir.css');
      Yii::app()->clientScript->registerCssFile($baseUrl . '/css/themes/tooltipster-punk.css');
      Yii::app()->clientScript->registerCssFile($baseUrl . '/css/themes/tooltipster-light.css');

      Yii::app()->clientScript->registerScriptFile($baseUrl . '/js/jquery.tooltipster.js', CClientScript::POS_HEAD);
  .....