Examine source code of Remember the Sidebar

{
  "version": "1.1resigned1",
  "applications": {
    "gecko": {
      "id": "rtm-sidebar@mikeconley.ca",
      "strict_min_version": "54.0"
    }
  },
  "description": "Opens Remember The Milk in the Firefox sidebar.",
  "manifest_version": 2,
  "name": "Remember the Sidebar",
  "sidebar_action": {
    "default_title": "Remember the Sidebar",
    "default_panel": "sidebar.html",
    "browser_style": false
  }
}