Examine source code of ffCK Overlays

{
  "manifest_version": 2,
  "name": "ffCK Overlays",
  "description": "Right-click any overlay to remove it. Inspired by the Chrome extension \"F*ck Overlays\" (https://chrome.google.com/webstore/detail/fck-overlays/ppedokobpbdajgiejhnjfbdjlgobcpkp).",
  "version": "1.1resigned1",
  "homepage_url": "https://github.com/mashedkeyboard/ffckoverlays",
  "icons": {
    "48": "icons/ext-48.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "activeTab",
    "menus"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{72f01d74-e2f1-4581-b6a3-451b45523783}"
    }
  }
}