Examine source code of Lite Calendar

{
  "manifest_version" : 2 ,
  "name" : "Simple Calendar",
  "version" : "1.0",
  "description" : "A lightweight calendar addon for Firefox.",
  "icons" : {
    "48" : "icon.png"
  },
  "browser_action" : {
    "default_popup" : "popup.html",
    "default_icon" : "icon.png"
  },
  "permissions" : [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{21d5ed0a-36f9-4fa0-9b05-42be74c9aac1}"
    }
  }
}