Examine source code of Tab Manager Plus

{
  "manifest_version": 2,
  "name": "Tab Manager Plus",
  "version": "1.0",
  "description": "A simple tab manager for Firefox",
  "icons": {
    "48": "logo.png"
  },
  "permissions": [
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "logo.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a4956a20-ecdb-444c-a110-45069f8a7a61}"
    }
  }
}