add: flavourList["text/x-moz-url"] = { width: 2, iid: "nsISupportsWString" }; 
context:   getSupportedFlavours: function ()    {      var flavourList = { };      flavourList["application/x-moz-file"] = { width: 2, iid: "nsIFile" };      return flavourList;    }  
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/8c6d09b89b487c70d9d2dc8574ce73f23857e2c9/MsgComposeCommands.js/buggy/mailnews/compose/resources/content/MsgComposeCommands.js