Used Firefox Add-on Builder and the extension doesn't work

Thought i would try to build and extension for firefox so I used the Add-on Builder to build a basic extension at MDC. When I click 开发者_开发百科the extension in the Tools menu it is ment to bring up a hello world popup, but it doesn't.

I think its the onLoad function fails to fetch the data from nigol-strings. But if its a generated code from the MDC website why does it have errors or is it me?

var nigol = {
  onLoad: function() {
    // initialization code
    this.initialized = true;
    this.strings = document.getElementById("nigol-strings");
  },

  onMenuItemCommand: function(e) {
    var promptService = Components.classes["@mozilla.org/embedcomp/prompt-service;1"]
                                  .getService(Components.interfaces.nsIPromptService);
    promptService.alert(window, this.strings.getString("helloMessageTitle"),
                                this.strings.getString("helloMessage"));
  }
};

window.addEventListener("load", nigol.onLoad, false);

Like i said I downloaded from the addon builder and have not made any alterations.

Thanks

The way you're calling onLoad, the value of this in that function is not what you think it is. Try this instead:

window.addEventListener("load", function() { nigol.onLoad(); }, false);