Examine source code of Other Window

{
  "description": "Open or send a tab to a different window with the click of a button.",
  "manifest_version": 2,
  "name": "Other Window",
  "version": "5.1.0",
  "homepage_url": "https://gitlab.com/juszczakn/other-win",
  "icons": {
    "48": "icons/otherwin-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5df6e133-f35d-4c62-885a-56387df22f6b}",
      "strict_min_version": "79.0"
    }
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "storage",
    "sessions",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/otherwin-32.png",
    "default_title": "Other Win",
    "default_popup": "web/popup/other_window.html"
  },
  "background": {
    "page": "web/background.html"
  },
  "options_ui": {
    "page": "web/options/options.html"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+O"
      },
      "description": "Open 'Other Window'"
    }
  }
}