Examine source code of Tweetdeck for sidebar

{
  "manifest_version": 2,
  "name": "Tweetdeck sidebar",
  "description": "You can display tweetdeck in the sidebar.",
  "version": "1.1resigned1",
  "applications": {
    "gecko": {
      "strict_min_version": "54.0a1",
      "id": "{31219780-6443-49aa-a196-76fad2ddfa8e}"
    }
  },
  "icons": {
    "512": "icons/icon512.png"
  },
  "sidebar_action": {
    "default_icon": {
      "48": "icons/icon_48.png",
      "96": "icons/icon_96.png"
    },
    "default_title": "Tweetdeck",
    "default_panel": "index.html"
  },
  "permissions": [
    "storage",
    "tabs"
  ]
}