title: Safari Extension: "on install" event?
body: <p>I am developing an extension for Safari 6 and I want to set some default values for my settings. These default values depend on <code>window.navigator.language</code>, so setting them in <code>Settings.plist</code> does not the trick – I need to run some JS code to set them.</p>
  
  <p>Obviously, this code should only run once right after install. And it shouldn't run after simply reenabling the extension.</p>
  
  <p>Is there an "official" event that I can attach a function with <code>addEventlistener</code> to? Or do I really need the <a href="https://stackoverflow.com/questions/9868985/safari-extension-first-run-and-updates">trick with setting a helper variable</a>?</p>