Examine source code of Privacy Screen

{
  "manifest_version": 2,
  "name": "Privacy Screen",
  "version": "1.0",
  "description": "Privacy Screen is a firefox extension that hides webpages when your mouse is not hovering on your window.",
  "icons": {
    "48": "icons/privacy.svg",
    "96": "icons/privacy.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "privacyscreen.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{bbddae62-3532-45bc-b183-0293cb50036d}"
    }
  }
}