/**
  * Triggers event actions.
  */
 public function __construct()
 {
     // @todo check the count of posts of the button post type.
     $_oPostCount = wp_count_posts(AmazonAutoLinks_Registry::$aPostTypes['button']);
     if (!is_object($_oPostCount)) {
         return;
     }
     // If a button exists, return
     if (isset($_oPostCount->publish) && $_oPostCount->publish <= 0) {
         // Otherwise, create one.
         $this->_createDefaultButton();
     }
     // Update the button CSS option.
     update_option(AmazonAutoLinks_Registry::$aOptionKeys['button_css'], AmazonAutoLinks_PluginUtility::getCSSRulesOfActiveButtons());
 }
 /**
  * Updates the active button CSS rules.
  * @callback    action  shutdown
  */
 public function replyToUpdateButtonCSSOnShutdown()
 {
     update_option(AmazonAutoLinks_Registry::$aOptionKeys['button_css'], AmazonAutoLinks_PluginUtility::getCSSRulesOfActiveButtons());
 }