Examine source code of ResizeFFWidth

{
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{76c052a3-213d-4052-afc5-79cd01acf6ef}",
      "strict_min_version": "88.0"
    }
  },
  "name": "ResizeFFWidth",
  "version": "20.1",
  "description": "Resize Firefox window width.",
  "icons": {
    "32": "rw32.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "rw32.png",
    "default_title": "ResizeFFWidth",
    "default_popup": "popup.html"
  },
  "permissions": [
    "tabs"
  ]
}