/**
  * Append a button to a certain container
  *
  * @param array $p Hash array with named parameters (as used in skin templates)
  * @param string $container Container name where the buttons should be added to
  * @see rcube_remplate::button()
  */
 public function add_button($p, $container)
 {
     if ($this->api->output->type == 'html') {
         // fix relative paths
         foreach (array('imagepas', 'imageact', 'imagesel') as $key) {
             if ($p[$key]) {
                 $p[$key] = $this->api->url . $this->resource_url($p[$key]);
             }
         }
         $this->api->add_content($this->api->output->button($p), $container);
     }
 }