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

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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);