Examine source code of TabReturn

{
  "name": "TabReturn",
  "version": "1.0.1",
  "description": "Simulate 'keep browser open when the last tab is closed' behavior.",
  "browser_action": {},
  "background": {
    "scripts": [
      "script.js"
    ],
    "persistent": false
  },
  "permissions": [
    "tabs"
  ],
  "icons": {
    "16": "icons/ic0_16px.png",
    "32": "icons/ic0_32px.png",
    "48": "icons/ic0_48px.png",
    "128": "icons/ic0_128px.png"
  },
  "manifest_version": 2,
  "homepage_url": "https://www.backup0.pw/tabreturn",
  "update_url": "https://edge.microsoft.com/extensionwebstorebase/v1/crx",
  "browser_specific_settings": {
    "gecko": {
      "id": "{a6c6a3fb-3e3c-4779-b6fc-9a918675decc}"
    }
  }
}