Examine source code of MultiButton

{
  "description": "MultiButton",
  "manifest_version": 2,
  "name": "MultiButton",
  "version": "0.2.1",
  "icons": {
    "48": "ui/icons/logo.svg"
  },
  "applications": {
    "gecko": {
      "id": "muitibutton-we@gchristensen.github.io",
      "strict_min_version": "91.0"
    }
  },
  "background": {
    "page": "background.html"
  },
  "browser_action": {
    "default_icon": "ui/icons/logo.svg"
  },
  "options_ui": {
    "page": "ui/options.html",
    "open_in_tab": true
  },
  "permissions": [
    "contextMenus",
    "storage",
    "downloads"
  ]
}