Examine source code of Select Tabs in Group

{
  "author": "igorlogius",
  "homepage_url": "https://github.com/igorlogius/webextensions/tree/main/select-tabs-in-group",
  "description": "Select all tabs in a tabgroup",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_area": "navbar"
  },
  "commands": {
    "_execute_browser_action": {}
  },
  "icons": {},
  "manifest_version": 2,
  "name": "Select Tabs in Group",
  "permissions": [
    "tabGroups",
    "tabs",
    "menus"
  ],
  "version": "1.0.3",
  "browser_specific_settings": {
    "gecko": {
      "id": "{d118f6df-0c9b-40d7-ba2e-00dad130ce71}"
    }
  }
}