Examine source code of Tabatus

{
  "description": "Quickly search & switch tabs by keyboard.",
  "icons": {
    "16": "resources/icon-16.png",
    "32": "resources/icon-32.png",
    "64": "resources/icon-64.png"
  },
  "homepage_url": "https://github.com/jokokko/tabatus",
  "manifest_version": 3,
  "name": "tabatus",
  "default_locale": "en",
  "options_ui": {
    "page": "options.html",
    "browser_style": false
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "action": {
    "default_icon": {
      "16": "resources/icon-16.png",
      "32": "resources/icon-32.png"
    },
    "default_title": "Tabatus",
    "default_popup": "tabpanel.html"
  },
  "commands": {
    "_execute_action": {
      "suggested_key": {
        "default": "Ctrl+Period"
      }
    }
  },
  "version": "2.2.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "@tabatus",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}